codex-mcp-tool

Codex MCP Server

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MCP server connecting Claude/Cursor to Codex CLI. Enables code analysis via @ file references, multi-turn conversations, sandboxed edits, and structured change mode.

Features

• File Analysis — Reference files with @src/, @package.json syntax
• Multi-Turn Sessions — Conversation continuity with workspace isolation
• Native Resume — Uses codex resume for context preservation (CLI v0.36.0+)
• Local OSS Models — Run with Ollama or LM Studio via localProvider
• Web Search — Research capabilities with search: true
• Sandbox Mode — Safe automation with explicit sandbox and approval policies
• Change Mode — Structured OLD/NEW patch output for refactoring
• Brainstorming — SCAMPER, design-thinking, lateral thinking frameworks
• Health Diagnostics — CLI version, features, and session monitoring
• Cross-Platform — Windows, macOS, Linux fully supported

Quick Start

claude mcp add codex-cli -- npx -y @trishchuk/codex-mcp-tool

Prerequisites: Node.js 18+, Codex CLI installed and authenticated.

Configuration

{
  "mcpServers": {
    "codex-cli": {
      "command": "npx",
      "args": ["-y", "@trishchuk/codex-mcp-tool"]
    }
  }
}

Config locations: macOS: ~/Library/Application Support/Claude/claude_desktop_config.json | Windows: %APPDATA%\Claude\claude_desktop_config.json

Usage Examples

// File analysis
'explain the architecture of @src/';
'analyze @package.json and list dependencies';

// With specific model
'use codex with model gpt-5.6-sol to analyze @algorithm.py';

// Multi-turn conversations (v1.4.0+)
'ask codex sessionId:"my-project" prompt:"explain @src/"';
'ask codex sessionId:"my-project" prompt:"now add error handling"';

// Brainstorming
'brainstorm ways to optimize CI/CD using SCAMPER method';

// Sandbox mode
'use codex sandbox:true to create and run a Python script';

// Web search
'ask codex search:true prompt:"latest TypeScript 5.7 features"';

// Local OSS model (Ollama)
'ask codex localProvider:"ollama" model:"qwen3:8b" prompt:"explain @src/"';

Tools

| Tool | Description | | ---------------- | ------------------------------------------------------------------- | | ask-codex | Execute Codex CLI with files, models, sessions, and safety controls | | batch-codex | Run multiple atomic Codex tasks sequentially or concurrently | | review-changes | Run the native non-interactive Codex review command | | do-act | Execute, verify with a shell command, and retry fixes | | brainstorm | Generate ideas with structured creative frameworks | | list-sessions | View, delete, or clear MCP conversation mappings | | list-skills | List skills visible from the selected workspace | | health | Diagnose CLI installation, version, features, and sessions | | fetch-chunk | Retrieve a chunk from cached change-mode output | | ping | Test the MCP connection | | help | Return current codex --help output | | version | Report Codex CLI, Node.js, platform, and package versions | | timeout-test | Exercise keepalive and timeout behavior |

Models

By default the model parameter is omitted and Codex CLI applies the default model from your ~/.codex/config.toml (for example model = "gpt-5.6-sol"). Pass model only when you need to override the configured default for a single call. Reasoning depth is calibrated per tool:

• ask-codex — uses the Codex CLI default reasoning (medium). Increase it only when the task needs more planning or checking.
• brainstorm, do-act, review-changes — default reasoningEffort: "high" (creative ideation, act-check-fix loops, and code review benefit from deeper reasoning).

| Model | Recommendation | | --------------- | ------------------------------------------------------ | | gpt-5.6-sol | Complex, ambiguous, high-value work; strongest default | | gpt-5.6-terra | Everyday coding with a better capability/cost balance | | gpt-5.6-luna | Clear, repeatable, high-volume tasks | | gpt-5.5 | Previous-generation fallback | | gpt-5.4 | Professional coding fallback | | gpt-5.4-mini | Small, fast, cost-efficient fallback |

GPT-5.6 Sol and Terra can expose max and ultra reasoning. ultra may delegate work to subagents; most tasks should remain on medium or high.

Key Features

Session Management (v1.4.0+)

Multi-turn conversations with workspace isolation:

{ "prompt": "analyze code", "sessionId": "my-session" }
{ "prompt": "continue from here", "sessionId": "my-session" }
{ "prompt": "start fresh", "sessionId": "my-session", "resetSession": true }

Environment:

• CODEX_SESSION_TTL_MS - Session TTL (default: 24h)
• CODEX_MAX_SESSIONS - Max sessions (default: 50)

Codex CLI version

Requires Codex CLI 0.95.0 or newer. On older versions the server fails with an explicit upgrade message rather than silently dropping unsupported flags. Upgrade with npm install -g @openai/codex@latest; run the health tool to see the detected version.

Troubleshooting: "codex not found"

MCP clients launched from a GUI (Dock, Finder, Start menu) inherit a minimal PATH that excludes Homebrew, nvm, and volta directories, so codex may work from a terminal but not from the app. The server searches those locations automatically; if it still cannot find the CLI, pin it explicitly:

{ "env": { "CODEX_CLI_PATH": "/opt/homebrew/bin/codex" } }

Find the value with which codex. Run the health tool to see which executable was resolved and how.

Local OSS Models (v1.6.0+)

Run with local Ollama or LM Studio instead of OpenAI:

// Ollama
{ "prompt": "analyze @src/", "localProvider": "ollama", "model": "qwen3:8b" }

// LM Studio
{ "prompt": "analyze @src/", "localProvider": "lmstudio", "model": "my-model" }

// Auto-select provider
{ "prompt": "analyze @src/", "oss": true }

Requirements: Ollama running locally with a model that supports tool calling (e.g. qwen3:8b).

Advanced Options

| Parameter | Description | | ---------------------- | ------------------------------------------------- | | model | Model selection | | sessionId | Enable conversation continuity | | sandbox | Compatibility automation: workspace-write + never | | search | Enable web search | | changeMode | Structured OLD/NEW edits | | addDirs | Additional writable directories | | toolOutputTokenLimit | Cap response verbosity (100-10,000) | | reasoningEffort | low, medium, high, xhigh, max, ultra | | oss | Use local OSS model provider | | localProvider | Local provider: lmstudio or ollama | | strictConfig | Fail on unknown Codex configuration keys | | ephemeral | Do not persist Codex session files | | ignoreUserConfig | Ignore $CODEX_HOME/config.toml | | ignoreRules | Ignore execpolicy .rules files |

CLI Compatibility

Validated against Codex CLI 0.144.3. The server keeps older feature guards, but current releases are recommended. Notable current behavior:

• --full-auto and approval policy on-failure have been removed by Codex CLI.
• MCP sandbox: true / fullAuto: true remain compatibility aliases for

--sandbox workspace-write --ask-for-approval never; they do not bypass the sandbox.

• Native --search is used without the deprecated web_search_request feature.
• Current exec flags include --strict-config, --ephemeral,

--ignore-user-config, and --ignore-rules.

Troubleshooting

codex --version    # Check CLI version
codex login        # Authenticate

Use health tool for diagnostics: 'use health verbose:true'

Migration

v2.3.x → v2.4.0: Codex CLI 0.144.3 compatibility audit; added GPT-5.6 Sol/Terra/Luna, max/ultra reasoning, current exec flags, native-only search, and safe compatibility handling for the removed --full-auto flag and on-failure approval policy.

Current CLI compatibility: added GPT-5.6 Sol/Terra/Luna, max/ultra reasoning, current exec flags, native-only search, and safe expansion of the removed --full-auto compatibility option.

v2.2.x → v2.3.0: gpt-5.5 as new default, added gpt-5.4-mini, dropped retired models (gpt-5.3-codex-spark, gpt-5.2-codex, gpt-5.1-codex-max, gpt-5.1-codex-mini).

v2.0.x → v2.1.0: gpt-5.4 as new default model, updated fallback chain.

v1.5.x → v1.6.0: Local OSS model support (localProvider, oss), gpt-5.3-codex default model, xhigh reasoning effort.

v1.3.x → v1.4.0: New sessionId parameter, list-sessions/health tools, structured error handling. No breaking changes.

License

MIT License. Not affiliated with OpenAI.

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Documentation | Issues | Inspired by jamubc/gemini-mcp-tool