diff --git a/pyproject.toml b/pyproject.toml
index 7d1a322b2..f239b195d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,7 +15,7 @@ dependencies = [
     "aiosqlite>=0.20.0",
     "greenlet>=3.1.1",
     "pydantic[email,timezone]>=2.12.0",
-    "mcp>=1.23.1",
+    "mcp>=2,<3",
     "pydantic-settings>=2.6.1",
     "loguru>=0.7.3",
     "pyright>=1.1.390",
@@ -29,7 +29,7 @@ dependencies = [
     "alembic>=1.14.1",
     "pillow>=11.1.0",
     "pybars3>=0.9.7",
-    "fastmcp>=3.3.1,<4",
+    "fastmcp==4.0.0b1",
     "pyjwt>=2.10.1",
     "python-dotenv>=1.1.0",
     "pytest-aio>=1.9.0",
@@ -149,6 +149,9 @@ dev = [
 [tool.hatch.version]
 source = "uv-dynamic-versioning"
 
+[tool.uv]
+constraint-dependencies = ["fastmcp-slim==4.0.0b1"]
+
 [tool.uv-dynamic-versioning]
 vcs = "git"
 style = "pep440"
diff --git a/src/basic_memory/cli/commands/command_utils.py b/src/basic_memory/cli/commands/command_utils.py
index 0360be1fe..bc993aea6 100644
--- a/src/basic_memory/cli/commands/command_utils.py
+++ b/src/basic_memory/cli/commands/command_utils.py
@@ -65,8 +65,8 @@ async def run_project_index(
         force_full: If True, force a full scan bypassing watermark optimization
         run_in_background: If True, return immediately; if False, wait for completion
     """
-    # Deferred: ToolError lives in the mcp SDK, which must not load at CLI startup (#886).
-    from mcp.server.fastmcp.exceptions import ToolError
+    # Deferred: ToolError lives in FastMCP's runtime, which must not load at CLI startup (#886).
+    from fastmcp.exceptions import ToolError
 
     # Resolve default project so get_client() can route per-project
     project = project or ConfigManager().default_project
@@ -99,8 +99,8 @@ async def run_project_index(
 
 async def get_project_info(project: str):
     """Get project information via API endpoint."""
-    # Deferred: ToolError lives in the mcp SDK, which must not load at CLI startup (#886).
-    from mcp.server.fastmcp.exceptions import ToolError
+    # Deferred: ToolError lives in FastMCP's runtime, which must not load at CLI startup (#886).
+    from fastmcp.exceptions import ToolError
 
     try:
         async with get_client(project_name=project) as client:
diff --git a/src/basic_memory/cli/commands/doctor.py b/src/basic_memory/cli/commands/doctor.py
index 43a2afb79..1d4539cd2 100644
--- a/src/basic_memory/cli/commands/doctor.py
+++ b/src/basic_memory/cli/commands/doctor.py
@@ -64,8 +64,8 @@ async def _delete_doctor_project(
     project_client: ProjectClient, project_name: str, project_id: str
 ) -> None:
     """Delete the generated doctor project without weakening the public API guard."""
-    # Deferred: ToolError lives in the mcp SDK, which must not load at CLI startup (#886).
-    from mcp.server.fastmcp.exceptions import ToolError
+    # Deferred: ToolError lives in FastMCP's runtime, which must not load at CLI startup (#886).
+    from fastmcp.exceptions import ToolError
 
     try:
         await project_client.delete_project(project_id)
@@ -203,8 +203,8 @@ def doctor(
     cloud: bool = typer.Option(False, "--cloud", help="Force cloud API routing"),
 ) -> None:
     """Run local consistency checks to verify file/database indexing."""
-    # Deferred: ToolError lives in the mcp SDK, which must not load at CLI startup (#886).
-    from mcp.server.fastmcp.exceptions import ToolError
+    # Deferred: ToolError lives in FastMCP's runtime, which must not load at CLI startup (#886).
+    from fastmcp.exceptions import ToolError
 
     try:
         validate_routing_flags(local, cloud)
diff --git a/src/basic_memory/cli/commands/orphans.py b/src/basic_memory/cli/commands/orphans.py
index 40cce8ad3..851e4412b 100644
--- a/src/basic_memory/cli/commands/orphans.py
+++ b/src/basic_memory/cli/commands/orphans.py
@@ -49,8 +49,8 @@ def orphans(
     """
     from basic_memory.cli.commands.command_utils import run_with_cleanup
 
-    # Deferred: ToolError lives in the mcp SDK, which must not load at CLI startup (#886).
-    from mcp.server.fastmcp.exceptions import ToolError
+    # Deferred: ToolError lives in FastMCP's runtime, which must not load at CLI startup (#886).
+    from fastmcp.exceptions import ToolError
 
     try:
         validate_routing_flags(local, cloud)
diff --git a/src/basic_memory/cli/commands/status.py b/src/basic_memory/cli/commands/status.py
index 8f0a40bbc..483a9354c 100644
--- a/src/basic_memory/cli/commands/status.py
+++ b/src/basic_memory/cli/commands/status.py
@@ -131,8 +131,8 @@ def status(
     """
     from basic_memory.cli.commands.command_utils import run_with_cleanup
 
-    # Deferred: ToolError lives in the mcp SDK, which must not load at CLI startup (#886).
-    from mcp.server.fastmcp.exceptions import ToolError
+    # Deferred: ToolError lives in FastMCP's runtime, which must not load at CLI startup (#886).
+    from fastmcp.exceptions import ToolError
 
     # Trigger: --wait with a negative --timeout
     # Why: a negative deadline times out on the very first poll, producing a confusing
diff --git a/src/basic_memory/mcp/client_info.py b/src/basic_memory/mcp/client_info.py
index 65ac7c08a..adb175b7e 100644
--- a/src/basic_memory/mcp/client_info.py
+++ b/src/basic_memory/mcp/client_info.py
@@ -15,7 +15,7 @@
 
 
 class MCPClientInfoMiddleware(Middleware):
-    """Persist sanitized initialize clientInfo in FastMCP session state."""
+    """Persist sanitized initialize client info as a legacy-session fallback."""
 
     @override
     async def on_initialize(
@@ -34,16 +34,34 @@ async def on_initialize(
 
 
 async def is_openai_mcp_client(context: Context | None) -> bool:
-    """Return whether the current MCP session identified itself as OpenAI's MCP client."""
+    """Return whether the current request identified itself as OpenAI's MCP client."""
     if context is None:
         return False
 
+    request_client_info = client_info_from_context(context)
+    if request_client_info is not None:
+        return client_info_is_openai_mcp(request_client_info)
+
     return client_info_is_openai_mcp(await context.get_state(MCP_CLIENT_INFO_STATE_KEY))
 
 
 def client_info_from_initialize(message: mt.InitializeRequest) -> ClientInfoState | None:
-    """Extract the normalized clientInfo payload from an initialize request."""
-    client_info = message.params.clientInfo
+    """Extract the normalized client info payload from an initialize request."""
+    return _client_info_from_implementation(message.params.client_info)
+
+
+def client_info_from_context(context: Context) -> ClientInfoState | None:
+    """Extract the client identity attached to the current FastMCP request."""
+    request_context = context.request_context
+    if request_context is None:
+        return None
+    client_params = request_context.session.client_params
+    if client_params is None:
+        return None
+    return _client_info_from_implementation(client_params.client_info)
+
+
+def _client_info_from_implementation(client_info: mt.Implementation) -> ClientInfoState | None:
     return _client_info_from_mapping(
         {
             "name": client_info.name,
diff --git a/src/basic_memory/mcp/project_context.py b/src/basic_memory/mcp/project_context.py
index ed2628149..3aa6e137e 100644
--- a/src/basic_memory/mcp/project_context.py
+++ b/src/basic_memory/mcp/project_context.py
@@ -825,8 +825,8 @@ async def resolve_project_and_path(
         # Why: allow project-scoped memory URLs without requiring a separate project parameter
         # Outcome: attempt to resolve the prefix as a project and route to it
         if project_prefix:
-            # Deferred: ToolError lives in the mcp SDK, which must not load at CLI startup (#886).
-            from mcp.server.fastmcp.exceptions import ToolError
+            # Deferred: ToolError lives in FastMCP's runtime, which must not load at CLI startup (#886).
+            from fastmcp.exceptions import ToolError
 
             if cached_project and _project_matches_identifier(cached_project, project_prefix):
                 resolved_project = await resolve_project_parameter(project_prefix, context=context)
@@ -1026,8 +1026,8 @@ async def get_project_client(
         is_factory_mode,
     )
 
-    # Deferred: ToolError lives in the mcp SDK, which must not load at CLI startup (#886).
-    from mcp.server.fastmcp.exceptions import ToolError
+    # Deferred: ToolError lives in FastMCP's runtime, which must not load at CLI startup (#886).
+    from fastmcp.exceptions import ToolError
 
     # When project_id (UUID) is provided, prefer it as the resolution identifier.
     # external_id is unambiguous across workspaces; project name can collide.
diff --git a/src/basic_memory/mcp/tools/build_context.py b/src/basic_memory/mcp/tools/build_context.py
index 9160674ad..f1cda95a7 100644
--- a/src/basic_memory/mcp/tools/build_context.py
+++ b/src/basic_memory/mcp/tools/build_context.py
@@ -250,7 +250,7 @@ async def build_context(
         try:
             depth = int(depth)
         except ValueError:
-            from mcp.server.fastmcp.exceptions import ToolError
+            from fastmcp.exceptions import ToolError
 
             raise ToolError(f"Invalid depth parameter: '{depth}' is not a valid integer")
 
diff --git a/src/basic_memory/mcp/tools/delete_note.py b/src/basic_memory/mcp/tools/delete_note.py
index c0963efce..172a9b147 100644
--- a/src/basic_memory/mcp/tools/delete_note.py
+++ b/src/basic_memory/mcp/tools/delete_note.py
@@ -3,7 +3,7 @@
 
 from loguru import logger
 from fastmcp import Context
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 from pydantic import AliasChoices, Field
 
 from basic_memory.config import ConfigManager
diff --git a/src/basic_memory/mcp/tools/edit_note.py b/src/basic_memory/mcp/tools/edit_note.py
index a08dc8a71..736b6f5db 100644
--- a/src/basic_memory/mcp/tools/edit_note.py
+++ b/src/basic_memory/mcp/tools/edit_note.py
@@ -6,7 +6,7 @@
 from httpx import HTTPStatusError
 from loguru import logger
 from fastmcp import Context
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 from pydantic import AliasChoices, BeforeValidator, Field
 
 if TYPE_CHECKING:  # pragma: no cover
diff --git a/src/basic_memory/mcp/tools/move_note.py b/src/basic_memory/mcp/tools/move_note.py
index cbcb3835c..83e57a348 100644
--- a/src/basic_memory/mcp/tools/move_note.py
+++ b/src/basic_memory/mcp/tools/move_note.py
@@ -6,7 +6,7 @@
 
 from loguru import logger
 from fastmcp import Context
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 from pydantic import AliasChoices, Field
 
 from basic_memory.config import ConfigManager
diff --git a/src/basic_memory/mcp/tools/read_content.py b/src/basic_memory/mcp/tools/read_content.py
index 957577b10..563b0354d 100644
--- a/src/basic_memory/mcp/tools/read_content.py
+++ b/src/basic_memory/mcp/tools/read_content.py
@@ -14,7 +14,7 @@
 from PIL import Image as PILImage
 from fastmcp import Context
 from pydantic import AliasChoices, Field
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.config import ConfigManager
 from basic_memory.mcp.project_context import (
diff --git a/src/basic_memory/mcp/tools/utils.py b/src/basic_memory/mcp/tools/utils.py
index 87a11a7be..f68dba85e 100644
--- a/src/basic_memory/mcp/tools/utils.py
+++ b/src/basic_memory/mcp/tools/utils.py
@@ -30,7 +30,7 @@
     RequestExtensions,
 )
 from loguru import logger
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.config import ConfigManager
 
diff --git a/test-int/mcp/test_param_aliases_integration.py b/test-int/mcp/test_param_aliases_integration.py
index 4c4760165..ce9ce978d 100644
--- a/test-int/mcp/test_param_aliases_integration.py
+++ b/test-int/mcp/test_param_aliases_integration.py
@@ -581,14 +581,14 @@ async def test_aliases_not_advertised_in_schema(mcp_server, app):
 
         for tool_name, (must_have, must_not_have) in checks.items():
             assert tool_name in tools, f"tool {tool_name} not registered"
-            props = tools[tool_name].inputSchema["properties"]
+            props = tools[tool_name].input_schema["properties"]
             for canonical in must_have:
                 assert canonical in props, f"{tool_name}: canonical '{canonical}' missing"
             for alias in must_not_have:
                 assert alias not in props, f"{tool_name}: alias '{alias}' leaked into schema"
 
         # #818: AliasChoices on optional bool broke external-client JSON schema (null-only).
-        overwrite_schema = tools["write_note"].inputSchema["properties"]["overwrite"]
+        overwrite_schema = tools["write_note"].input_schema["properties"]["overwrite"]
         schema_types: set[str] = set()
         if "type" in overwrite_schema:
             raw = overwrite_schema["type"]
diff --git a/test-int/mcp/test_project_management_integration.py b/test-int/mcp/test_project_management_integration.py
index 346d2b181..098854b78 100644
--- a/test-int/mcp/test_project_management_integration.py
+++ b/test-int/mcp/test_project_management_integration.py
@@ -254,12 +254,8 @@ async def test_delete_current_project_protection(mcp_server, app, test_project):
 
         # Should show error about deleting current project
         error_message = str(exc_info.value)
-        assert "delete_project" in error_message
-        assert (
-            "currently active" in error_message
-            or "test-project" in error_message
-            or "Switch to a different project" in error_message
-        )
+        assert "Cannot delete default project" in error_message
+        assert "test-project" in error_message
 
 
 @pytest.mark.asyncio
diff --git a/test-int/mcp/test_ui_sdk_integration.py b/test-int/mcp/test_ui_sdk_integration.py
index d5d26d069..a0ccf37b5 100644
--- a/test-int/mcp/test_ui_sdk_integration.py
+++ b/test-int/mcp/test_ui_sdk_integration.py
@@ -39,7 +39,7 @@ async def test_search_notes_ui_embedded_resource(mcp_server, app, test_project):
         assert len(result.content) == 1
         block = result.content[0]
         assert block.type == "resource"
-        assert block.resource.mimeType == "text/html"
+        assert block.resource.mime_type == "text/html"
         assert "<!doctype html>" in block.resource.text.lower()
         assert block.resource.meta is not None
         assert "mcpui.dev/ui-initial-render-data" in block.resource.meta
@@ -70,7 +70,7 @@ async def test_read_note_ui_embedded_resource(mcp_server, app, test_project):
         assert len(result.content) == 1
         block = result.content[0]
         assert block.type == "resource"
-        assert block.resource.mimeType == "text/html"
+        assert block.resource.mime_type == "text/html"
         assert "<!doctype html>" in block.resource.text.lower()
         assert block.resource.meta is not None
         assert "mcpui.dev/ui-initial-render-data" in block.resource.meta
diff --git a/tests/cli/test_orphans_command.py b/tests/cli/test_orphans_command.py
index d06c7b3f4..262e3b154 100644
--- a/tests/cli/test_orphans_command.py
+++ b/tests/cli/test_orphans_command.py
@@ -4,7 +4,7 @@
 from contextlib import asynccontextmanager, nullcontext
 from unittest.mock import AsyncMock, MagicMock, patch
 
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 from typer.testing import CliRunner
 
 from basic_memory.cli.main import app as cli_app
diff --git a/tests/cli/test_project_info_errors.py b/tests/cli/test_project_info_errors.py
index 74306df10..60ef15f6c 100644
--- a/tests/cli/test_project_info_errors.py
+++ b/tests/cli/test_project_info_errors.py
@@ -5,7 +5,7 @@
 
 import pytest
 import typer
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 from typer.testing import CliRunner
 
 from basic_memory.cli.app import app
diff --git a/tests/mcp/conftest.py b/tests/mcp/conftest.py
index 44d7e4dcf..7d53b946c 100644
--- a/tests/mcp/conftest.py
+++ b/tests/mcp/conftest.py
@@ -6,8 +6,8 @@
 import pytest
 import pytest_asyncio
 from fastapi import FastAPI
+from fastmcp import FastMCP
 from httpx import AsyncClient, ASGITransport
-from mcp.server import FastMCP
 
 from basic_memory.api.app import app as fastapi_app
 from basic_memory.deps import get_engine_factory, get_app_config
@@ -25,6 +25,7 @@ class ContextState:
 
     def __init__(self):
         self._state: dict[str, object] = {}
+        self.request_context = None
 
     async def get_state(self, key: str):
         return self._state.get(key)
diff --git a/tests/mcp/test_client_info.py b/tests/mcp/test_client_info.py
index e6ffd944c..782b5bce5 100644
--- a/tests/mcp/test_client_info.py
+++ b/tests/mcp/test_client_info.py
@@ -2,10 +2,11 @@
 
 from __future__ import annotations
 
-from typing import Any, cast
+from typing import Any, cast, Literal
 
 import mcp.types as mt
 import pytest
+from fastmcp import Client, Context, FastMCP
 from fastmcp.server.middleware import CallNext, MiddlewareContext
 
 from basic_memory.mcp.client_info import (
@@ -21,6 +22,7 @@ class FakeMCPContext:
 
     def __init__(self) -> None:
         self.state: dict[str, object] = {}
+        self.request_context = None
 
     async def set_state(self, key: str, value: object) -> None:
         self.state[key] = value
@@ -39,9 +41,9 @@ def _initialize_context(
     return MiddlewareContext(
         message=mt.InitializeRequest(
             params=mt.InitializeRequestParams(
-                protocolVersion="2025-06-18",
+                protocol_version="2025-06-18",
                 capabilities=mt.ClientCapabilities(),
-                clientInfo=mt.Implementation(name=name, title=title, version=version),
+                client_info=mt.Implementation(name=name, title=title, version=version),
             )
         ),
         fastmcp_context=cast(Any, fastmcp_context),
@@ -86,7 +88,7 @@ async def call_next(inner_context: MiddlewareContext[mt.InitializeRequest]) -> s
 
 @pytest.mark.asyncio
 async def test_is_openai_mcp_client_reads_session_state() -> None:
-    """The gate accepts OpenAI's versioned clientInfo label."""
+    """Legacy sessions can still use client info captured during initialization."""
     context = FakeMCPContext()
     await context.set_state(
         MCP_CLIENT_INFO_STATE_KEY,
@@ -96,6 +98,28 @@ async def test_is_openai_mcp_client_reads_session_state() -> None:
     assert await is_openai_mcp_client(cast(Any, context)) is True
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize("mode", ["auto", "legacy"])
+async def test_is_openai_mcp_client_reads_request_identity(
+    mode: Literal["auto", "legacy"],
+) -> None:
+    """Modern and legacy protocols expose identity on each FastMCP request."""
+    server = FastMCP("client-info-test")
+
+    @server.tool
+    async def identify(context: Context) -> bool:
+        return await is_openai_mcp_client(context)
+
+    async with Client(
+        server,
+        client_info=mt.Implementation(name="openai-mcp", version="1.0.0"),
+        mode=mode,
+    ) as client:
+        result = await client.call_tool("identify", {})
+
+    assert result.data is True
+
+
 @pytest.mark.asyncio
 async def test_is_openai_mcp_client_rejects_missing_context() -> None:
     """No context means no authenticated MCP clientInfo to trust."""
diff --git a/tests/mcp/test_client_telemetry.py b/tests/mcp/test_client_telemetry.py
index 53443ab82..37c46b183 100644
--- a/tests/mcp/test_client_telemetry.py
+++ b/tests/mcp/test_client_telemetry.py
@@ -8,7 +8,7 @@
 import httpx
 import logfire
 import pytest
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 from typing import Any
 
 knowledge_client_module = importlib.import_module("basic_memory.mcp.clients.knowledge")
diff --git a/tests/mcp/test_project_context.py b/tests/mcp/test_project_context.py
index 0677f723e..c6474e5b6 100644
--- a/tests/mcp/test_project_context.py
+++ b/tests/mcp/test_project_context.py
@@ -1642,7 +1642,7 @@ async def test_get_project_client_with_cloud_project_id_routes_to_workspace_with
         WorkspaceProjectEntry,
         _build_workspace_project_index,
     )
-    from mcp.server.fastmcp.exceptions import ToolError
+    from fastmcp.exceptions import ToolError
 
     config = config_manager.load_config()
     config.projects["hermes-memory"] = ProjectEntry(
@@ -1985,7 +1985,7 @@ async def test_resolve_project_and_path_keeps_workspace_qualified_canonical_path
     config_manager,
     monkeypatch,
 ):
-    from mcp.server.fastmcp.exceptions import ToolError
+    from fastmcp.exceptions import ToolError
 
     from basic_memory.mcp.project_context import resolve_project_and_path
     from basic_memory.schemas.project_info import ProjectItem
@@ -2033,7 +2033,7 @@ async def test_resolve_project_and_path_preserves_personal_workspace_prefix(
     config_manager,
     monkeypatch,
 ):
-    from mcp.server.fastmcp.exceptions import ToolError
+    from fastmcp.exceptions import ToolError
 
     from basic_memory.mcp.project_context import resolve_project_and_path
     from basic_memory.schemas.project_info import ProjectItem
@@ -2114,7 +2114,7 @@ async def test_resolve_project_and_path_uses_cached_workspace_for_active_route(
     config_manager,
     monkeypatch,
 ):
-    from mcp.server.fastmcp.exceptions import ToolError
+    from fastmcp.exceptions import ToolError
 
     import basic_memory.mcp.project_context as project_context
     from basic_memory.mcp.project_context import resolve_project_and_path
@@ -2436,7 +2436,7 @@ async def test_local_route_clears_stale_cached_workspace(self, config_manager, m
         """A previous cloud workspace must not decorate later local memory URLs."""
         from contextlib import asynccontextmanager
 
-        from mcp.server.fastmcp.exceptions import ToolError
+        from fastmcp.exceptions import ToolError
 
         import basic_memory.mcp.project_context as project_context
         from basic_memory.config import ProjectEntry
@@ -3235,7 +3235,7 @@ async def test_resolve_project_and_path_keeps_patterns_project_qualified(
     Direct URLs keep workspace qualification (the link resolver handles them);
     patterns have no resolver fallback and must match the index form.
     """
-    from mcp.server.fastmcp.exceptions import ToolError
+    from fastmcp.exceptions import ToolError
 
     from basic_memory.mcp.project_context import resolve_project_and_path
     from basic_memory.schemas.project_info import ProjectItem
diff --git a/tests/mcp/test_project_context_scoped_key.py b/tests/mcp/test_project_context_scoped_key.py
index bb037bc91..540e512d4 100644
--- a/tests/mcp/test_project_context_scoped_key.py
+++ b/tests/mcp/test_project_context_scoped_key.py
@@ -3,7 +3,7 @@
 from typing import Any, cast
 
 import pytest
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.mcp.project_context import resolve_project_and_path
 from basic_memory.schemas.project_info import ProjectItem
diff --git a/tests/mcp/test_tool_build_context.py b/tests/mcp/test_tool_build_context.py
index c2c71039b..7276867cf 100644
--- a/tests/mcp/test_tool_build_context.py
+++ b/tests/mcp/test_tool_build_context.py
@@ -2,7 +2,7 @@
 
 import pytest
 
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.mcp.tools import build_context, write_note
 
diff --git a/tests/mcp/test_tool_contracts.py b/tests/mcp/test_tool_contracts.py
index 6deecd431..89e13cc0b 100644
--- a/tests/mcp/test_tool_contracts.py
+++ b/tests/mcp/test_tool_contracts.py
@@ -252,13 +252,13 @@ async def test_mcp_tool_annotations_meet_directory_requirements():
         annotations = tool.to_mcp_tool().annotations
         assert annotations is not None, f"Tool '{tool_name}' has no annotations"
         assert annotations.title, f"Tool '{tool_name}' is missing annotations.title"
-        assert annotations.readOnlyHint is expected["readOnlyHint"], (
+        assert annotations.read_only_hint is expected["readOnlyHint"], (
             f"Tool '{tool_name}' readOnlyHint should be {expected['readOnlyHint']}"
         )
-        assert annotations.destructiveHint is expected["destructiveHint"], (
+        assert annotations.destructive_hint is expected["destructiveHint"], (
             f"Tool '{tool_name}' destructiveHint should be {expected['destructiveHint']}"
         )
-        assert annotations.openWorldHint is False, (
+        assert annotations.open_world_hint is False, (
             f"Tool '{tool_name}' openWorldHint should be False"
         )
 
@@ -269,7 +269,7 @@ async def test_edit_note_operation_schema_exposes_supported_operations():
     tool_list = await mcp.list_tools()
     edit_note_tool = next(tool for tool in tool_list if tool.name == "edit_note")
 
-    input_schema = edit_note_tool.to_mcp_tool().inputSchema
+    input_schema = edit_note_tool.to_mcp_tool().input_schema
     operation_schema = input_schema["properties"]["operation"]
 
     assert operation_schema["type"] == "string"
diff --git a/tests/mcp/test_tool_edit_note.py b/tests/mcp/test_tool_edit_note.py
index bfa1069dc..7b88727a7 100644
--- a/tests/mcp/test_tool_edit_note.py
+++ b/tests/mcp/test_tool_edit_note.py
@@ -5,7 +5,7 @@
 
 import httpx
 import pytest
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.mcp.clients import KnowledgeClient
 from basic_memory.mcp.tools.edit_note import _resolve_after_disk_recovery, edit_note
diff --git a/tests/mcp/test_tool_read_content.py b/tests/mcp/test_tool_read_content.py
index 64e591340..f205eff62 100644
--- a/tests/mcp/test_tool_read_content.py
+++ b/tests/mcp/test_tool_read_content.py
@@ -11,7 +11,7 @@
 from types import SimpleNamespace
 
 import pytest
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.mcp.tools import read_content, write_note
 
diff --git a/tests/mcp/test_tool_recent_activity.py b/tests/mcp/test_tool_recent_activity.py
index 8ee7fb9e7..9f69dcd82 100644
--- a/tests/mcp/test_tool_recent_activity.py
+++ b/tests/mcp/test_tool_recent_activity.py
@@ -5,7 +5,7 @@
 
 import pytest
 
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.mcp.tools import recent_activity
 from basic_memory.schemas.search import SearchItemType
diff --git a/tests/mcp/test_tool_resource.py b/tests/mcp/test_tool_resource.py
index 265ce83d6..6d18ca986 100644
--- a/tests/mcp/test_tool_resource.py
+++ b/tests/mcp/test_tool_resource.py
@@ -5,7 +5,7 @@
 from PIL import Image as PILImage
 
 import pytest
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.mcp.tools import read_content, write_note
 from basic_memory.mcp.tools.read_content import (
diff --git a/tests/mcp/test_tool_utils.py b/tests/mcp/test_tool_utils.py
index da9dfe8d9..f0a719921 100644
--- a/tests/mcp/test_tool_utils.py
+++ b/tests/mcp/test_tool_utils.py
@@ -4,8 +4,8 @@
 
 import httpx
 import pytest
+from fastmcp.exceptions import ToolError
 from httpx import HTTPStatusError, Request
-from mcp.server.fastmcp.exceptions import ToolError
 
 from basic_memory.mcp.tools.utils import (
     call_delete,
@@ -98,6 +98,7 @@ async def test_call_get_error(mock_response):
     with pytest.raises(ToolError) as exc:
         await call_get(_client(client), "http://test.com")
     assert "Resource not found" in str(exc.value)
+    assert isinstance(exc.value.__cause__, HTTPStatusError)
 
 
 @pytest.mark.asyncio
diff --git a/tests/mcp/test_tool_utils_cloud_auth.py b/tests/mcp/test_tool_utils_cloud_auth.py
index 9c412be8d..da63053b8 100644
--- a/tests/mcp/test_tool_utils_cloud_auth.py
+++ b/tests/mcp/test_tool_utils_cloud_auth.py
@@ -4,7 +4,7 @@
 
 import pytest
 from httpx import HTTPStatusError, Request
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.mcp.tools.utils import call_post
 
diff --git a/tests/mcp/tools/test_mutating_memory_url_routing.py b/tests/mcp/tools/test_mutating_memory_url_routing.py
index 6ef3772e1..7026966bd 100644
--- a/tests/mcp/tools/test_mutating_memory_url_routing.py
+++ b/tests/mcp/tools/test_mutating_memory_url_routing.py
@@ -3,7 +3,7 @@
 import importlib
 
 import pytest
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 
 from basic_memory.mcp.tools.delete_note import delete_note
 from basic_memory.mcp.tools.move_note import move_note
diff --git a/tests/mcp/tools/test_search_notes_multi_project.py b/tests/mcp/tools/test_search_notes_multi_project.py
index b088ce238..ac35262f6 100644
--- a/tests/mcp/tools/test_search_notes_multi_project.py
+++ b/tests/mcp/tools/test_search_notes_multi_project.py
@@ -4,7 +4,7 @@
 import importlib
 
 from httpx import HTTPStatusError, Request, Response
-from mcp.server.fastmcp.exceptions import ToolError
+from fastmcp.exceptions import ToolError
 import pytest
 
 from basic_memory.schemas.search import SearchItemType, SearchResponse, SearchResult
diff --git a/uv.lock b/uv.lock
index df31cd178..01be96f5f 100644
--- a/uv.lock
+++ b/uv.lock
@@ -10,6 +10,9 @@ resolution-markers = [
     "python_full_version < '3.13' and sys_platform != 'win32'",
 ]
 
+[manifest]
+constraints = [{ name = "fastmcp-slim", specifier = "==4.0.0b1" }]
+
 [[package]]
 name = "aiofile"
 version = "3.11.1"
@@ -370,7 +373,7 @@ requires-dist = [
     { name = "dateparser", specifier = ">=1.2.0" },
     { name = "fastapi", extras = ["standard"], specifier = ">=0.136.1" },
     { name = "fastembed", specifier = ">=0.7.4" },
-    { name = "fastmcp", specifier = ">=3.3.1,<4" },
+    { name = "fastmcp", specifier = "==4.0.0b1" },
     { name = "filelock", specifier = ">=3.12" },
     { name = "greenlet", specifier = ">=3.1.1" },
     { name = "httpx", specifier = ">=0.28.0" },
@@ -378,7 +381,7 @@ requires-dist = [
     { name = "logfire", specifier = ">=4.19.0" },
     { name = "loguru", specifier = ">=0.7.3" },
     { name = "markdown-it-py", specifier = ">=3.0.0" },
-    { name = "mcp", specifier = ">=1.23.1" },
+    { name = "mcp", specifier = ">=2,<3" },
     { name = "mdformat", specifier = ">=0.7.22" },
     { name = "mdformat-frontmatter", specifier = ">=2.0.8" },
     { name = "mdformat-gfm", specifier = ">=0.3.7" },
@@ -1099,21 +1102,22 @@ wheels = [
 
 [[package]]
 name = "fastmcp"
-version = "3.4.4"
+version = "4.0.0b1"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "fastmcp-slim", extra = ["client", "server"] },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/9c/f7/5188565d1b93ad611cbd80bf473e7ad669d1f3b689c4bedcd304e1ec3472/fastmcp-3.4.4.tar.gz", hash = "sha256:378202e26ec15b23819d9a1c0d1b0ebda096bc712720532010a0b82a45c2b1df", size = 28796458, upload-time = "2026-07-09T00:32:41.352Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/eb/fd/e513c524bb3e296203f65bd8e9e726e9236bd3b59315e7cbdeb095662c01/fastmcp-4.0.0b1.tar.gz", hash = "sha256:f98d69588a73e1672840558641d5d0f111e207baffe001f3465713a53ebb6b4c", size = 42065171, upload-time = "2026-07-28T21:18:15.312Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/5f/67/3cef84ba38a23dca1e1e776bfda8a35ab3c7a6c94a8ca81d0715de6dd3c5/fastmcp-3.4.4-py3-none-any.whl", hash = "sha256:f86f208713212260068cf55c32936839eee856fefc7808e18a032f31eb0f718e", size = 8019, upload-time = "2026-07-09T00:32:39.411Z" },
+    { url = "https://files.pythonhosted.org/packages/2c/66/41b503ef852eff83f3f0c04f46cd1fc738c5374fd509384fc6b96e45918f/fastmcp-4.0.0b1-py3-none-any.whl", hash = "sha256:d66eb7b0763ffff2ae0fc573778ea25604dcb7e59769e5afaf9851a806eb1129", size = 8064, upload-time = "2026-07-28T21:18:12.688Z" },
 ]
 
 [[package]]
 name = "fastmcp-slim"
-version = "3.4.4"
+version = "4.0.0b1"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
+    { name = "mcp-types" },
     { name = "platformdirs" },
     { name = "pydantic", extra = ["email"] },
     { name = "pydantic-settings" },
@@ -1121,16 +1125,16 @@ dependencies = [
     { name = "rich" },
     { name = "typing-extensions" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/45/79/f35661c6a1d76dfbe17a079f912d96fffcfdd40fad5a9144bb9e7dfb1fdf/fastmcp_slim-3.4.4.tar.gz", hash = "sha256:dcaa3e0be2127d7eacdce592c2ef0039204923dc0ec396454615cb4a3275b078", size = 590203, upload-time = "2026-07-09T00:32:20.531Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/bc/33/f207166aac88c6d8be1b2a82c54fecd1e04b075ef12d027aa17b3134fc0f/fastmcp_slim-4.0.0b1.tar.gz", hash = "sha256:158efb25720e0cb301711146b2d05d181de95cd91fe70e87c251ad14b123d665", size = 660081, upload-time = "2026-07-28T21:17:50.171Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/16/91/321e0b2e9ed70d0628b17ddaec76fc7b09f3e1d5d290f70bf101a2890142/fastmcp_slim-3.4.4-py3-none-any.whl", hash = "sha256:9d3a6327b9ee835188eb7323fc3b5d4cd061631b48da8ece56794bb538972505", size = 765158, upload-time = "2026-07-09T00:32:19.11Z" },
+    { url = "https://files.pythonhosted.org/packages/90/5d/fbe192d2ab50bb31b284fd0eb6c72d4347df7a57d836bee4f1973ffd1d7d/fastmcp_slim-4.0.0b1-py3-none-any.whl", hash = "sha256:dd907a3db5a2f479ca958c30157e227b4f7b340a56d333eb91de95719254597a", size = 827975, upload-time = "2026-07-28T21:17:48.747Z" },
 ]
 
 [package.optional-dependencies]
 client = [
     { name = "authlib" },
     { name = "exceptiongroup" },
-    { name = "httpx" },
+    { name = "httpx2" },
     { name = "mcp" },
     { name = "opentelemetry-api" },
     { name = "py-key-value-aio", extra = ["filetree", "keyring", "memory"] },
@@ -1141,7 +1145,7 @@ server = [
     { name = "cyclopts" },
     { name = "exceptiongroup" },
     { name = "griffelib" },
-    { name = "httpx" },
+    { name = "httpx2" },
     { name = "joserfc" },
     { name = "jsonref" },
     { name = "jsonschema-path" },
@@ -1561,6 +1565,19 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/7e/f5/f66802a942d491edb555dd61e3a9961140fd64c90bce1eafd741609d334d/httpcore-1.0.9-py3-none-any.whl", hash = "sha256:2d400746a40668fc9dec9810239072b40b4484b640a8c38fd654a024c7a1bf55", size = 78784, upload-time = "2025-04-24T22:06:20.566Z" },
 ]
 
+[[package]]
+name = "httpcore2"
+version = "2.9.1"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "h11" },
+    { name = "truststore" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/39/a8/20ed1ed79cbc2ecdf5301c0968ab7c85547212e2a7bd126ddd2d986e206e/httpcore2-2.9.1.tar.gz", hash = "sha256:4d8acbf8b306f48c9d6046591fd5ba4037d1b1b1000d140fc2c3eab1e9a0c0e2", size = 67089, upload-time = "2026-07-24T09:21:03.867Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/9f/fb/46c52b781975c335a2bcf1072c7bbc007cbdc8d674217f5ee1daba2c848b/httpcore2-2.9.1-py3-none-any.whl", hash = "sha256:6182472379e855fe4221246a2bb7ecede403bc61c6798062ae1787d051ccde26", size = 82809, upload-time = "2026-07-24T09:21:01.178Z" },
+]
+
 [[package]]
 name = "httptools"
 version = "0.8.0"
@@ -1613,12 +1630,19 @@ wheels = [
 ]
 
 [[package]]
-name = "httpx-sse"
-version = "0.4.3"
+name = "httpx2"
+version = "2.9.1"
 source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/0f/4c/751061ffa58615a32c31b2d82e8482be8dd4a89154f003147acee90f2be9/httpx_sse-0.4.3.tar.gz", hash = "sha256:9b1ed0127459a66014aec3c56bebd93da3c1bc8bb6618c8082039a44889a755d", size = 15943, upload-time = "2025-10-10T21:48:22.271Z" }
+dependencies = [
+    { name = "anyio" },
+    { name = "httpcore2" },
+    { name = "idna" },
+    { name = "truststore" },
+    { name = "typing-extensions", marker = "python_full_version < '3.13'" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/21/14/38128fbafd7e0ed41d874df6c9a653d47c2d111cfe59e2b4ac95161b4abd/httpx2-2.9.1.tar.gz", hash = "sha256:1932a768737e3666291582833da748cc4e563c337cf96706fccc04fa6e58764a", size = 95458, upload-time = "2026-07-24T09:21:04.972Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/d2/fd/6668e5aec43ab844de6fc74927e155a3b37bf40d7c3790e49fc0406b6578/httpx_sse-0.4.3-py3-none-any.whl", hash = "sha256:0ac1c9fe3c0afad2e0ebb25a934a59f4c7823b60792691f779fad2c5568830fc", size = 8960, upload-time = "2025-10-10T21:48:21.158Z" },
+    { url = "https://files.pythonhosted.org/packages/13/b8/cfd91c4ab9134d386d48f0b6ac662ff3d4be6efdee59ee1c67ebc3c0487c/httpx2-2.9.1-py3-none-any.whl", hash = "sha256:1820fe14a9ab1107bfeff39259987429450b070ec0ff38cc87eb0d8c97fdc71a", size = 91191, upload-time = "2026-07-24T09:21:02.6Z" },
 ]
 
 [[package]]
@@ -2096,15 +2120,15 @@ wheels = [
 
 [[package]]
 name = "mcp"
-version = "1.28.1"
+version = "2.0.0"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "anyio" },
-    { name = "httpx" },
-    { name = "httpx-sse" },
+    { name = "httpx2" },
     { name = "jsonschema" },
+    { name = "mcp-types" },
+    { name = "opentelemetry-api" },
     { name = "pydantic" },
-    { name = "pydantic-settings" },
     { name = "pyjwt", extra = ["crypto"] },
     { name = "python-multipart" },
     { name = "pywin32", marker = "sys_platform == 'win32'" },
@@ -2114,9 +2138,22 @@ dependencies = [
     { name = "typing-inspection" },
     { name = "uvicorn", marker = "sys_platform != 'emscripten'" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/6e/77/9450b8f251a13affb6281997d0523c4615f8a8b35d0b21ff30db3a5aac9d/mcp-1.28.1.tar.gz", hash = "sha256:d51e36a5f5644faea4f85ea649bfffa6bc6c26770d42798ad6a3de3d2ba69683", size = 638501, upload-time = "2026-06-26T12:57:29.093Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/74/33/32d4dff2c95bb5d897c3ef4c83649a08996b17b58f0a326d2495d4c81179/mcp-2.0.0.tar.gz", hash = "sha256:0f440e735c13ece8bb19bc62cf0b86f4313448432fbb77d35e14034f4e050728", size = 1662284, upload-time = "2026-07-28T13:45:32.346Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/67/72/7d7897418912c1d12e87556630dfb7bf0eac71160e9bef8b447960804ee3/mcp-2.0.0-py3-none-any.whl", hash = "sha256:1cb4c75d2d2c7b8c1d756355e5d82a39f2822cc7f13e22a2051d7ca3592349d6", size = 349980, upload-time = "2026-07-28T13:45:28.853Z" },
+]
+
+[[package]]
+name = "mcp-types"
+version = "2.0.0"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "pydantic" },
+    { name = "typing-extensions" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/bb/56/9b8e1c152f61f6c6b07c4b5896c88c7d0ae90bac6ee6306f852fcc5c1eb0/mcp_types-2.0.0.tar.gz", hash = "sha256:d7d939b9285c9961ae8866ba75ef85da34d12bafe276efbf4eb6a131786d8379", size = 66632, upload-time = "2026-07-28T13:45:33.804Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/e2/5e/d118fce19f87a2e7d8101c35c8ae0ec289098a4df0ff244cec23e415aca0/mcp-1.28.1-py3-none-any.whl", hash = "sha256:2726bca5e7193f61c5dde8b12500a6de2d9acf6d1a1c0be9e8c2e706437991df", size = 222620, upload-time = "2026-06-26T12:57:27.218Z" },
+    { url = "https://files.pythonhosted.org/packages/f5/4c/c78d78c3d52b0ac594ad7cc8ef5972adfe070e3597a8a4c6ce0cd39196ea/mcp_types-2.0.0-py3-none-any.whl", hash = "sha256:6b2de797ca2797f568b79529e1b25948e34de511bcc0bd82fef1039a6d1b8eb0", size = 69649, upload-time = "2026-07-28T13:45:30.713Z" },
 ]
 
 [[package]]
@@ -4169,6 +4206,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/22/2a/5e5e750890ada51017d18d0d4c30da696e5b5bd3180947729927628fc3cb/tqdm-4.68.4-py3-none-any.whl", hash = "sha256:5168118b2368f48c561afda8020fd79195b1bdb0bdf8086b88442c267a315dc2", size = 676612, upload-time = "2026-07-07T09:58:16.256Z" },
 ]
 
+[[package]]
+name = "truststore"
+version = "0.10.4"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/53/a3/1585216310e344e8102c22482f6060c7a6ea0322b63e026372e6dcefcfd6/truststore-0.10.4.tar.gz", hash = "sha256:9d91bd436463ad5e4ee4aba766628dd6cd7010cf3e2461756b3303710eebc301", size = 26169, upload-time = "2025-08-12T18:49:02.73Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/19/97/56608b2249fe206a67cd573bc93cd9896e1efb9e98bce9c163bcdc704b88/truststore-0.10.4-py3-none-any.whl", hash = "sha256:adaeaecf1cbb5f4de3b1959b42d41f6fab57b2b1666adb59e89cb0b53361d981", size = 18660, upload-time = "2025-08-12T18:49:01.46Z" },
+]
+
 [[package]]
 name = "ty"
 version = "0.0.64"