Codex MCP Code Review

Run Codex app-server reviews of uncommitted changes via an MCP tool. Compared to the built-in /review, this keeps review context clean while fixes happen in the main session that retains implementation knowledge, reducing regressions and enabling longer autonomous runs with better code quality.

Requirements

• Codex CLI installed and authenticated.

• uv installed.

Related MCP server: copilot-mcp-server

Configure Codex (MCP)

Codex loads MCP servers from ~/.codex/config.toml and supports configuring them via the codex mcp CLI.

Review profile (recommended)

Profile example (gpt-5.5, medium reasoning effort):

# ~/.codex/config.toml
[profiles.review]
model = "gpt-5.5"
model_reasoning_effort = "medium"

When the MCP server is started with --profile review, it reads this profile from Codex config and applies supported review settings itself. Supported profile keys are model, model_provider, service_tier, model_reasoning_effort, and model_reasoning_summary.

AGENTS.md example instruction:

for verification call `review_uncommitted_changes: runs=1` until no issues

Tool timeout (required)

Set tool_timeout_sec for the MCP server in ~/.codex/config.toml to a value larger than the review timeout (--timeout-seconds passed to the server command). Example: if the review timeout is 2700 seconds, set tool_timeout_sec = 3000.

Option A: CLI (recommended)

This registers a stdio MCP server that Codex launches when a session starts.

codex mcp add codex-code-review -- \
  uv run -m mcp_code_review.server --parallelism 1 --concurrency-mode auto --timeout-seconds 2700 \
  --profile review

The codex mcp add workflow is the supported way to add MCP servers from the CLI. After adding the server, set tool_timeout_sec in ~/.codex/config.toml (see Option B) so it is higher than --timeout-seconds.

Additional review instructions are enabled by default. Existing configurations that include --enable additional_review_instructions still work for backward compatibility.

To disable additional review instructions, add:

--disable additional_review_instructions

Option B: config.toml

Add an MCP server entry in ~/.codex/config.toml:

[mcp_servers.codex-code-review]
command = "uv"
tool_timeout_sec = 3000
args = [
  "run",
  "-m",
  "mcp_code_review.server",
  "--parallelism",
  "1",
  "--concurrency-mode",
  "auto",
  "--timeout-seconds",
  "2700",
  "--profile",
  "review"
]

Codex reads MCP server entries from the mcp_servers table in ~/.codex/config.toml.

Configure with uvx (run directly from Git)

If you prefer not to clone locally, you can run the server directly from the Git repository using uvx.

Repository: https://github.com/Szpadel/codex-mcp-code-review

Codex (CLI)

codex mcp add codex-code-review-uvx -- \
  uvx --from git+https://github.com/Szpadel/codex-mcp-code-review \
  python -m mcp_code_review.server --parallelism 1 --concurrency-mode auto --timeout-seconds 2700 \
  --profile review

Codex (config.toml)

[mcp_servers.codex-code-review-uvx]
command = "uvx"
tool_timeout_sec = 3000
args = [
  "--from",
  "git+https://github.com/Szpadel/codex-mcp-code-review",
  "python",
  "-m",
  "mcp_code_review.server",
  "--parallelism",
  "1",
  "--concurrency-mode",
  "auto",
  "--timeout-seconds",
  "2700",
  "--profile",
  "review"
]

Claude Code (.mcp.json)

{
  "mcpServers": {
    "codex-code-review-uvx": {
      "command": "uvx",
      "args": [
        "--from",
        "git+https://github.com/Szpadel/codex-mcp-code-review",
        "python",
        "-m",
        "mcp_code_review.server",
        "--parallelism",
        "1",
        "--concurrency-mode",
        "auto",
        "--timeout-seconds",
        "2700",
        "--profile",
        "review"
      ],
      "env": {}
    }
  }
}

Developer mode (run from source path)

If you want Codex to run the server directly from this source checkout, point uv at the project path.

CLI

codex mcp add codex-code-review-dev -- \
  uv run --project /absolute/path/to/codex-mcp-code-review -m mcp_code_review.server \
  --parallelism 1 --concurrency-mode auto --timeout-seconds 2700 --profile review

config.toml

[mcp_servers.codex-code-review-dev]
command = "uv"
tool_timeout_sec = 3000
args = [
  "run",
  "--project",
  "/absolute/path/to/codex-mcp-code-review",
  "-m",
  "mcp_code_review.server",
  "--parallelism",
  "1",
  "--concurrency-mode",
  "auto",
  "--timeout-seconds",
  "2700",
  "--profile",
  "review"
]

Tool behavior

• Tool name: review_uncommitted_changes.

• Uses the native app-server review target uncommittedChanges (includes untracked files).

• Additional review instructions are enabled by default, exposing the additional_developer_instructions tool argument.

• When that argument is set, the server switches that run to a custom review target prompt built from a synced copy of Codex's native uncommitted-changes instructions and appends an Additional review instructions: section.

• Existing --enable additional_review_instructions usage is still accepted for backward compatibility.

• When disabled with --disable additional_review_instructions, the tool schema does not advertise additional_developer_instructions, and requests that send it anyway are rejected.

• Default runs: 4 (override by setting --parallelism on the MCP server config).

• Sandbox: read-only; approval policy: never.