grok-mcp

Use Grok (via the official xAI Grok CLI) as a peer code reviewer, adversary, and consultant inside Claude Code, Cursor, Cline, OpenClaw, and any other MCP host.

grok-mcp (npm: grok-cli-mcp) is a Model Context Protocol server that wraps the grok CLI. It gives your primary agent (Claude, Cursor, etc.) four tools so it can delegate to Grok for second opinions without leaving the session:

• grok_review — structured diff review with per-dimension scores
• grok_challenge — adversarial bug/race/security hunting
• grok_consult — multi-turn consultation (caller owns history)
• grok_chat — one-shot questions

English | 繁體中文

Why grok-mcp?

Most "Grok MCP" packages expose Grok's chat/search/image capabilities so Claude can use Grok. grok-mcp does the opposite: it lets your main coding agent (Claude/Cursor/…) ask Grok to review and attack its own work. A different model challenging your primary catches bugs single-model loops miss.

What you get

Four tools, all stateless, all stdout-only:

Prerequisites

• Node.js ≥ 18
• The Grok CLI installed:

  curl -fsSL https://x.ai/cli/install.sh | bash
  

• An auth method — either browser OAuth (grok once interactively) or an XAI_API_KEY from console.x.ai. See Authentication below.

Install

npm install -g grok-cli-mcp
# or use npx — no install needed
npx grok-cli-mcp

Why the npm name is grok-cli-mcp instead of grok-mcp? The bare grok-mcp name on npm was already taken by an unrelated project (a Grok HTTP-API integration). The brand, GitHub repo, and MCP server identity stay grok-mcp; only the npm install identifier is grok-cli-mcp — chosen to highlight that this server wraps the official Grok CLI.

Authentication

The wrapped Grok CLI supports two auth methods; grok-mcp inherits whichever is active.

Per xAI's auth precedence, XAI_API_KEY always wins over ~/.grok/auth.json. So you can keep your browser login for interactive grok use and override it just for this MCP server by setting XAI_API_KEY in the server's env block:

{
  "mcpServers": {
    "grok": {
      "command": "npx",
      "args": ["-y", "grok-cli-mcp"],
      "env": {
        "XAI_API_KEY": "xai-...",
        "GROK_MCP_TIMEOUT": "600000"
      }
    }
  }
}

Treat the key file as a secret — it ends up in your MCP host's config (e.g. ~/.claude.json), which is plain JSON on disk.

Wire it into your MCP host

Claude Code

Recommended — use add-json so the env block parses cleanly:

claude mcp add-json -s user grok '{
  "command": "npx",
  "args": ["-y", "grok-cli-mcp"],
  "env": { "XAI_API_KEY": "xai-...", "GROK_MCP_TIMEOUT": "600000" }
}'

Why add-json not claude mcp add -e ...? The -e KEY=val flag is variadic and will greedily consume the server name as another env value if you pass more than one. add-json sidesteps that footgun entirely.

Or edit ~/.claude.json directly. Minimal (OAuth fallback):

{
  "mcpServers": {
    "grok": {
      "command": "npx",
      "args": ["-y", "grok-cli-mcp"]
    }
  }
}

Cursor

Create .cursor/mcp.json (project) or ~/.cursor/mcp.json (global):

{
  "mcpServers": {
    "grok": {
      "command": "npx",
      "args": ["-y", "grok-cli-mcp"]
    }
  }
}

Cline (VS Code)

Settings → Cline → MCP Servers:

{
  "grok": {
    "command": "npx",
    "args": ["-y", "grok-cli-mcp"]
  }
}

Any other MCP host

grok-mcp speaks plain stdio MCP. Point any client at npx -y grok-cli-mcp and it works.

Tool reference

grok_chat

{ "prompt": "Explain consistent hashing in two sentences." }

Optional: model to override the default Grok model; timeout (seconds) to extend the per-call limit for long grok-4 reasoning. All four tools accept timeout.

grok_review

{ "base_ref": "main", "focus": "security" }

If diff is omitted, runs git diff <base_ref>...HEAD in cwd (defaults to your host's working directory). Returns a markdown review by default with verdict, per-dimension scores (correctness / readability / architecture / security / performance), and concrete fix-it items.

Pass "format": "json" to get machine-parseable output suitable for CI gating — see Use as a PR gate.

grok_consult

{
  "messages": [
    { "role": "system", "content": "You are a senior backend engineer." },
    { "role": "user", "content": "How would you cache this query?" },
    { "role": "assistant", "content": "Two options..." },
    { "role": "user", "content": "What's the failure mode of option 2?" }
  ]
}

The server is stateless — the caller passes the full thread each time. Most MCP hosts handle this naturally.

grok_challenge

{
  "code": "function transfer(from, to, amount) { from.balance -= amount; to.balance += amount; }",
  "context": "Node.js, called concurrently from HTTP handlers"
}

Returns severity-ranked issues (Critical / High / Medium / Low) with concrete reproductions and patches.

Configuration

Model defaults live in the Grok CLI itself (~/.grok/config.toml).

Timeouts

grok-4 is a reasoning model and long prompts routinely take longer than two minutes. The server's default per-call limit is 300s (5 min). You can change it three ways:

• Per call — pass timeout (seconds) to any tool: { "prompt": "...", "timeout": 600 }.
• Per server — set GROK_MCP_TIMEOUT (milliseconds) in the MCP server's env.
• Host side — the MCP host has its own request timeout that can fire before the server's. If calls still time out after raising the above, raise the host limit too. In Claude Code that's MCP_TIMEOUT (server startup) and MCP_TOOL_TIMEOUT (per tool call), both in milliseconds.

On timeout the error includes any partial output Grok produced before the deadline, so you don't lose a near-complete answer.

Use as a PR gate (CI)

grok-mcp ships a grok-review-ci bin and a composite GitHub Action so Grok can review every PR and fail the check on block.

Drop this into .github/workflows/grok-review.yml in your repo:

name: Grok review
on: { pull_request: { branches: [main] } }
permissions: { contents: read, pull-requests: write }
jobs:
  grok:
    runs-on: ubuntu-latest
    if: ${{ github.event.pull_request.head.repo.full_name == github.repository }}
    steps:
      - uses: actions/checkout@v4
        with: { fetch-depth: 0 }
      - uses: howardpen9/grok-mcp/.github/actions/grok-review@main
        with:
          xai-api-key: ${{ secrets.XAI_API_KEY }}
          gate-on: block      # also accepts: block,request_changes
          # focus: security   # optional
          # min-score: 6      # optional — fail any dimension below this

The action posts a sticky PR comment with verdict + per-dimension scores + concrete blockers, and exits non-zero (failing the check) when the verdict matches gate-on. Full example with comments: examples/workflows/grok-review.yml.

Want JSON straight from the tool instead? Pass format: "json" to grok_review — same schema as the bin emits, suitable for any pipeline:

{
  "verdict": "block",
  "summary": "Unparameterised SQL query in src/db.ts.",
  "scores": { "correctness": 4, "readability": 7, "architecture": 5, "security": 2, "performance": 8 },
  "blockers": [
    { "severity": "critical", "title": "SQL injection", "file": "src/db.ts", "line": 42,
      "reason": "User input concatenated directly into the query.",
      "fix": "Use the parameterised form `db.query(sql, [userId])`." }
  ],
  "notes": []
}

Roadmap

• v0.1 — four stateless tools, stdio transport
• Discoverability push (v0.1.3, shipped) — naming unification, MCP Registry, Smithery, glama.ai, stronger positioning. See docs/improvement-plan.md and CHANGELOG.md.
• v0.2 (current) — grok_review JSON mode + grok-review-ci bin + GitHub Action for PR gating.
• v0.3 — server-side session persistence so grok_consult can take a conversation_id
• v0.4 — streaming responses through MCP progress notifications

Development

git clone https://github.com/howardpen9/grok-mcp.git
cd grok-mcp
npm install
npm test
npm run build

License

MIT