From 4f204537d6da4a99d3b0d6f0b854237d6609036c Mon Sep 17 00:00:00 2001
From: Aiden Cline <aidenpcline@gmail.com>
Date: Fri, 3 Jul 2026 02:55:30 -0500
Subject: [PATCH 1/2] refactor(opencode): expose MCP tools in native shape from
 the service

---
 packages/opencode/src/mcp/index.ts     | 17 +++++++++++------
 packages/opencode/src/session/tools.ts |  4 +++-
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/packages/opencode/src/mcp/index.ts b/packages/opencode/src/mcp/index.ts
index e574e20fbaac..59053f13f3e7 100644
--- a/packages/opencode/src/mcp/index.ts
+++ b/packages/opencode/src/mcp/index.ts
@@ -1,7 +1,6 @@
 import path from "node:path"
 import { pathToFileURL } from "node:url"
 import { LayerNode } from "@opencode-ai/core/effect/layer-node"
-import { type Tool } from "ai"
 import { ConfigV1 } from "@opencode-ai/core/v1/config/config"
 import { serviceUse } from "@opencode-ai/core/effect/service-use"
 import { Client, type ClientOptions } from "@modelcontextprotocol/sdk/client/index.js"
@@ -154,11 +153,18 @@ export interface ServerInstructions {
   tools: string[]
 }
 
+/** An MCP tool in its native shape; consumers adapt it to their own tool format. */
+export interface McpTool {
+  def: MCPToolDef
+  client: MCPClient
+  timeout?: number
+}
+
 export interface Interface {
   readonly status: () => Effect.Effect<Record<string, Status>>
   readonly clients: () => Effect.Effect<Record<string, MCPClient>>
   readonly instructions: () => Effect.Effect<ServerInstructions[]>
-  readonly tools: () => Effect.Effect<Record<string, Tool>>
+  readonly tools: () => Effect.Effect<Record<string, McpTool>>
   readonly prompts: () => Effect.Effect<Record<string, PromptInfo & { client: string }>>
   readonly resources: (clientName?: string) => Effect.Effect<Record<string, ResourceInfo & { client: string }>>
   readonly resourceTemplates: (
@@ -656,7 +662,7 @@ const layer = Layer.effect(
     }
 
     const tools = Effect.fn("MCP.tools")(function* () {
-      const result: Record<string, Tool> = {}
+      const result: Record<string, McpTool> = {}
       const s = yield* InstanceState.get(state)
 
       const cfg = yield* cfgSvc.get()
@@ -672,9 +678,8 @@ const layer = Layer.effect(
           continue
         }
         const timeout = requestTimeout(s, clientName, mcpConfig, defaultTimeout)
-        for (const mcpTool of listed) {
-          const key = McpCatalog.toolName(clientName, mcpTool.name)
-          result[key] = McpCatalog.convertTool(mcpTool, client, timeout)
+        for (const def of listed) {
+          result[McpCatalog.toolName(clientName, def.name)] = { def, client, timeout }
         }
       }
       return result
diff --git a/packages/opencode/src/session/tools.ts b/packages/opencode/src/session/tools.ts
index 376ba8f2b861..449e83f32b69 100644
--- a/packages/opencode/src/session/tools.ts
+++ b/packages/opencode/src/session/tools.ts
@@ -3,6 +3,7 @@ import { SessionV1 } from "@opencode-ai/core/v1/session"
 import { Provider } from "@/provider/provider"
 import { ProviderTransform } from "@/provider/transform"
 import { MCP } from "@/mcp"
+import { McpCatalog } from "@/mcp/catalog"
 import { Permission } from "@/permission"
 import { Tool } from "@/tool/tool"
 import { ToolJsonSchema } from "@/tool/json-schema"
@@ -381,7 +382,8 @@ export const resolve = Effect.fn("SessionTools.resolve")(function* (input: {
     })
   }
 
-  for (const [key, item] of Object.entries(yield* mcp.tools())) {
+  for (const [key, entry] of Object.entries(yield* mcp.tools())) {
+    const item = McpCatalog.convertTool(entry.def, entry.client, entry.timeout)
     const execute = item.execute
     if (!execute) continue
 

From 135a0f87a57b68cd1e068f54749931261edfc3ae Mon Sep 17 00:00:00 2001
From: Aiden Cline <aidenpcline@gmail.com>
Date: Fri, 3 Jul 2026 03:02:30 -0500
Subject: [PATCH 2/2] refactor(opencode): mark McpTool fields readonly

---
 packages/opencode/src/mcp/index.ts | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/packages/opencode/src/mcp/index.ts b/packages/opencode/src/mcp/index.ts
index 59053f13f3e7..0d6c8c65dcdc 100644
--- a/packages/opencode/src/mcp/index.ts
+++ b/packages/opencode/src/mcp/index.ts
@@ -155,9 +155,10 @@ export interface ServerInstructions {
 
 /** An MCP tool in its native shape; consumers adapt it to their own tool format. */
 export interface McpTool {
-  def: MCPToolDef
-  client: MCPClient
-  timeout?: number
+  /** Shared cached definition; consumers must copy rather than mutate it. */
+  readonly def: MCPToolDef
+  readonly client: MCPClient
+  readonly timeout?: number
 }
 
 export interface Interface {