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Description
Terminal-Bench 2.0 Evaluation Results
First-ever benchmark evaluation of Hex on Terminal-Bench 2.0, the standard benchmark for evaluating AI coding agents in terminal environments. 89 tasks covering systems programming, security, data engineering, ML, and more.
Summary
| Configuration | Passed | Total | Solve Rate |
|---|---|---|---|
| Hex v1.11.2 + Claude Opus 4.6 | 43 | 88 | 48.9% |
| Hex v1.11.0 + Claude Sonnet 4.5 | 34 | 88 | 38.6% |
Leaderboard Context
| Agent | Model | Score | Rank |
|---|---|---|---|
| ForgeCode | Claude Opus 4.6 | 81.8% | #1 |
| Claude Code | Claude Opus 4.6 | 58.0% | #39 |
| Hex | Claude Opus 4.6 | 48.9% | ~#53 |
| Codex CLI | GPT-5 | 49.6% | #53 |
| Terminus 2 | Claude Sonnet 4.5 | 42.8% | #63 |
| Claude Code | Claude Sonnet 4.5 | 40.1% | #69 |
| Hex | Claude Sonnet 4.5 | 38.6% | ~#71 |
Hex with Opus 4.6 lands next to Codex CLI (GPT-5). With Sonnet 4.5, hex nearly matches Claude Code on the same model. The ~9 point gap to Claude Code on Opus is the primary improvement target.
Task-by-Task Results
Tasks Solved by Both Models (30 tasks)
| Task | Sonnet | Opus |
|---|---|---|
| bn-fit-modify | ✅ | ✅ |
| cobol-modernization | ✅ | ✅ |
| code-from-image | ✅ | ✅ |
| compile-compcert | ✅ | ✅ |
| constraints-scheduling | ✅ | ✅ |
| crack-7z-hash | ✅ | ✅ |
| custom-memory-heap-crash | ✅ | ✅ |
| extract-elf | ✅ | ✅ |
| fix-code-vulnerability | ✅ | ✅ |
| fix-git | ✅ | ✅ |
| fix-ocaml-gc | ✅ | ✅ |
| git-leak-recovery | ✅ | ✅ |
| git-multibranch | ✅ | ✅ |
| headless-terminal | ✅ | ✅ |
| large-scale-text-editing | ✅ | ✅ |
| log-summary-date-ranges | ✅ | ✅ |
| mcmc-sampling-stan | ✅ | ✅ |
| modernize-scientific-stack | ✅ | ✅ |
| multi-source-data-merger | ✅ | ✅ |
| nginx-request-logging | ✅ | ✅ |
| overfull-hbox | ✅ | ✅ |
| portfolio-optimization | ✅ | ✅ |
| prove-plus-comm | ✅ | ✅ |
| pypi-server | ✅ | ✅ |
| pytorch-model-cli | ✅ | ✅ |
| qemu-startup | ✅ | ✅ |
| rstan-to-pystan | ✅ | ✅ |
| sqlite-db-truncate | ✅ | ✅ |
| sqlite-with-gcov | ✅ | ✅ |
Tasks Solved Only by Opus 4.6 (13 tasks)
| Task | Category |
|---|---|
| break-filter-js-from-html | Web security |
| chess-best-move | Reasoning |
| count-dataset-tokens | Data processing |
| distribution-search | Statistics |
| feal-differential-cryptanalysis | Cryptography |
| financial-document-processor | Document parsing |
| kv-store-grpc | Systems programming |
| llm-inference-batching-scheduler | ML infrastructure |
| merge-diff-arc-agi-task | Complex diffing |
| password-recovery | Security |
| regex-log | Log parsing |
| reshard-c4-data | Data engineering |
| sanitize-git-repo | Git operations |
| tune-mjcf | Physics simulation |
Tasks Solved Only by Sonnet 4.5 (4 tasks)
| Task | Category |
|---|---|
| circuit-fibsqrt | Hardware design |
| hf-model-inference | ML inference |
| query-optimize | Database |
| schemelike-metacircular-eval | Language design |
| vulnerable-secret | Security |
Tasks Failed by Both (45 tasks)
adaptive-rejection-sampler, build-cython-ext, build-pmars, build-pov-ray, caffe-cifar-10, cancel-async-tasks, configure-git-webserver, db-wal-recovery, dna-assembly, dna-insert, extract-moves-from-video, feal-linear-cryptanalysis, filter-js-from-html, gcode-to-text, gpt2-codegolf, install-windows-3.11, largest-eigenval, mailman, make-doom-for-mips, make-mips-interpreter, model-extraction-relu-logits, mteb-leaderboard, mteb-retrieve, openssl-selfsigned-cert, path-tracing, path-tracing-reverse, polyglot-c-py, polyglot-rust-c, protein-assembly, pytorch-model-recovery, qemu-alpine-ssh, raman-fitting, regex-chess, sam-cell-seg, sparql-university, torch-pipeline-parallelism, torch-tensor-parallelism, train-fasttext, video-processing, winning-avg-corewars, write-compressor
Methodology
- Hex version: v1.11.0 (Sonnet run), v1.11.2 (Opus run)
- Agent mode:
--spell agent --permission-mode=auto(maximum intelligence spell, auto-approve tools) - Harness: Harbor with custom hex adapter (
hex-terminal-bench) - Infrastructure: Docker containers on aibox01, Cloudflare AI Gateway for API routing
- Concurrency: 4 parallel tasks
- Attempts: 1 attempt per task (no retries)
Agent Intelligence Features Used
These features were shipped as part of the v1.11.x release specifically to improve agent effectiveness (based on arXiv:2511.18538 survey findings):
- Enhanced system prompt — comprehensive guidance on tool usage, self-correction, planning, and code quality
- Agent spell (
--spell agent) — layers additional instructions for thorough planning, verification, and self-correction - Stuck detection — tracks consecutive tool failures and injects hints to try different approaches
- Verification hints — nudges to verify changes after file mutations
- Project memory — auto-detects project language, build/test commands, and structure
- Smarter context pruning — ContentBlock-aware token estimation, error prioritization
Improvement Opportunities
Closing the Gap to Claude Code (~9 points on Opus)
- Tool execution in mux path — the mux adapter creates a fresh Anthropic client per agent; optimizing tool call batching and streaming could reduce latency
- Extended thinking — Claude Code likely uses extended thinking; enabling this could improve complex reasoning tasks
- Better error recovery — many failed tasks show hex hitting errors and not recovering effectively; the stuck detection helps but could be more aggressive
- Task-specific context — injecting repository structure and file listings before the task prompt would help navigation
- Retry logic — running failed tasks with a different strategy (no spell, different prompt wrapping) could pick up a few more
Systemic Failures to Investigate
- Build tasks (build-pov-ray, build-pmars, build-cython-ext) — consistently fail, likely timeout or dependency issues in the container
- ML tasks (torch-, caffe-) — may need GPU or specific frameworks not available in the container
- Polyglot tasks — multi-language compilation chains are hard without verified tool outputs
Reproducing
# Install harbor
uv tool install harbor
# Clone hex-terminal-bench adapter
cd /path/to/hex-terminal-bench
# Install
uv venv && source .venv/bin/activate && uv pip install -e .
# Run
source /path/to/.env # needs ANTHROPIC_API_KEY and ANTHROPIC_BASE_URL
harbor run -d terminal-bench@2.0 \
--agent-import-path hex_terminal_bench:HexAgent \
-m anthropic/claude-opus-4-6 \
--ak version=1.11.2 \
--ae ANTHROPIC_API_KEY=$ANTHROPIC_API_KEY \
--ae ANTHROPIC_BASE_URL=$ANTHROPIC_BASE_URL \
--jobs-dir ./results \
--agent-setup-timeout-multiplier 3.0 \
-n 4
Activity
harperreed commentedon Mar 24, 2026
Updated Results: v1.12.0 with Extended Thinking + Multi-Model
Following the initial v1.11.x baseline, we shipped v1.12.0 with significant improvements and ran evaluations across 4 model configurations.
Score Progression
Best result: 54.5% with Opus 4.6 + extended thinking — up 15.9 points from the initial 38.6% baseline. Gap to Claude Code (58.0%) narrowed from 20 points to 3.5.
v1.12.0 Changes That Drove Improvement
Hex-side (v1.11.3 → v1.12.0):
mux v0.7.0 (critical):
Extended Thinking Impact
Tasks newly solved with thinking enabled (vs v1.11.2 Opus without):
extract-moves-from-video— video frame analysisfeal-linear-cryptanalysis— cryptanalysis (no model solved this before)largest-eigenval— numerical computingmake-mips-interpreter— MIPS CPU emulatorpath-tracing+path-tracing-reverse— ray tracing (heavy math)torch-pipeline-parallelism— distributed MLwrite-compressor— compression algorithm designbuild-pmars— build systemsopenssl-selfsigned-cert— crypto/securitysparql-university— knowledge graphsThese are all deep-reasoning tasks where extended thinking provides the most value.
Model Comparison: Tasks Solved
Union of all models: 66 unique tasks solved (75.0%)
Solved by all Anthropic configs (30 tasks): bn-fit-modify, cobol-modernization, code-from-image, constraints-scheduling, custom-memory-heap-crash, distribution-search, feal-differential-cryptanalysis, financial-document-processor, fix-code-vulnerability, fix-git, git-leak-recovery, headless-terminal, hf-model-inference, kv-store-grpc, large-scale-text-editing, llm-inference-batching-scheduler, log-summary-date-ranges, mcmc-sampling-stan, merge-diff-arc-agi-task, modernize-scientific-stack, multi-source-data-merger, nginx-request-logging, password-recovery, portfolio-optimization, prove-plus-comm, pypi-server, pytorch-model-cli, qemu-startup, reshard-c4-data, rstan-to-pystan
Opus 4.6 + thinking only (unique): extract-moves-from-video, feal-linear-cryptanalysis, largest-eigenval, make-mips-interpreter, path-tracing, path-tracing-reverse, torch-pipeline-parallelism, write-compressor
Sonnet 4.6 only (unique): adaptive-rejection-sampler, build-pov-ray, configure-git-webserver, qemu-alpine-ssh, tune-mjcf
GPT-5.4 Analysis
GPT-5.4 scored 31.8% — significantly below its capability (scores ~50%+ through Codex CLI). Root causes:
reasoning_effortwith tools on/v1/chat/completionsRemaining Gap to Claude Code (3.5 points)
The biggest remaining opportunities:
Reproducing v1.12.0 Results