codereviewbuddy 0.20.0

codereview buddy helps your AI agent interact with AI code review--smoothly!

codereviewbuddy

An MCP server that helps your AI coding agent interact with AI code reviewers — smoothly.

Manages review comments from Unblocked, Devin, and CodeRabbit on GitHub PRs with staleness detection, batch resolution, re-review triggering, and issue tracking.

[!WARNING] Bleeding edge. This server runs on Python 3.14 and FastMCP v3 prerelease (>=3.0.0rc1). FastMCP v3 is pre-release software — APIs may change before stable. We track it closely and pin versions in uv.lock for reproducibility, but be aware that upstream breaking changes are possible.

Features

Review comment management

• List review comments — inline threads, PR-level reviews, and bot comments (codecov, netlify, vercel, etc.) with reviewer identification and staleness detection
• Stacked PR support — list_stack_review_comments fetches comments across an entire PR stack in one call
• Resolve comments — individually or bulk-resolve stale ones (files changed since the review)
• Smart skip logic — resolve_stale_comments skips reviewers that auto-resolve their own comments (Devin, CodeRabbit), only batch-resolving threads from reviewers that don't (Unblocked)
• Reply to anything — inline review threads (PRRT_), PR-level reviews (PRR_), and bot issue comments (IC_) all routed to the correct GitHub API
• Request re-reviews — per-reviewer logic handles differences automatically (manual trigger for Unblocked, auto for Devin/CodeRabbit)

Issue tracking

• Create issues from review comments — turn useful AI suggestions into GitHub issues with labels, PR backlinks, file/line location, and quoted comment text

Server features (FastMCP v3)

• Typed output schemas — all tools return Pydantic models with JSON Schema, giving MCP clients structured data instead of raw strings
• Progress reporting — long-running operations report progress via FastMCP context (visible in MCP clients that support it)
• Production middleware — ErrorHandling (transforms exceptions to clean MCP errors with tracebacks), Timing (logs execution duration for every tool call), and Logging (request/response payloads for debugging)
• Update checker — check_for_updates compares the running version against PyPI and suggests upgrade commands
• Zero config auth — uses gh CLI, no PAT tokens or .env files

CLI testing (free with FastMCP v3)

FastMCP v3 gives you terminal testing of the server with no extra code:

# List all tools with their signatures
fastmcp list codereviewbuddy.server:mcp

# Call a tool directly from the terminal
fastmcp call codereviewbuddy.server:mcp list_review_comments pr_number=42

# Inspect server metadata
fastmcp inspect codereviewbuddy.server:mcp

# Run with MCP Inspector for interactive debugging
fastmcp dev codereviewbuddy.server:mcp

Prerequisites

• GitHub CLI (gh) installed and authenticated (gh auth login)
• Python 3.14+

Installation

This project uses uv. No install needed — run directly:

uvx codereviewbuddy

Or install permanently:

uv tool install codereviewbuddy

MCP Client Configuration

Windsurf

Add to your MCP settings (~/.codeium/windsurf/mcp_config.json):

{
  "mcpServers": {
    "codereviewbuddy": {
      "command": "uvx",
      "args": ["--prerelease=allow", "codereviewbuddy@latest"],
      "env": {
        "CRB_WORKSPACE": "/path/to/your/project"
      }
    }
  }
}

Why CRB_WORKSPACE? The server needs to know which project you're working in so gh CLI commands target the right repo. Without this, auto-detection may pick the wrong repository.

Why --prerelease=allow? codereviewbuddy depends on FastMCP v3 prerelease (>=3.0.0rc1). Without this flag, uvx refuses to resolve pre-release dependencies.

Why @latest? Without it, uvx caches the first resolved version and never upgrades automatically.

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "codereviewbuddy": {
      "command": "uvx",
      "args": ["--prerelease=allow", "codereviewbuddy@latest"],
      "env": {
        "CRB_WORKSPACE": "/path/to/your/project"
      }
    }
  }
}

Cursor

Add to .cursor/mcp.json in your project:

{
  "mcpServers": {
    "codereviewbuddy": {
      "command": "uvx",
      "args": ["--prerelease=allow", "codereviewbuddy@latest"],
      "env": {
        "CRB_WORKSPACE": "/path/to/your/project"
      }
    }
  }
}

Other major MCP clients (VS Code, Claude Code, Gemini CLI, ChatGPT, etc.)

For clients not listed above, use the MCP install-instructions generator to get the exact config block and file path for your client version:

• Hosted: https://hyprmcp.com/mcp-install-instructions-generator/
• CLI:

npx @hyprmcp/mcp-install-instructions-generator@latest codereviewbuddy --output md

You can target a specific client explicitly, for example:

npx @hyprmcp/mcp-install-instructions-generator@latest codereviewbuddy --target vscode --output md
npx @hyprmcp/mcp-install-instructions-generator@latest codereviewbuddy --target claude-code --output md
npx @hyprmcp/mcp-install-instructions-generator@latest codereviewbuddy --target gemini-cli --output md
npx @hyprmcp/mcp-install-instructions-generator@latest codereviewbuddy --target chatgpt --output md

Use the same runtime settings in every client:

{
  "mcpServers": {
    "codereviewbuddy": {
      "command": "uvx",
      "args": ["--prerelease=allow", "codereviewbuddy@latest"],
      "env": {
        "CRB_WORKSPACE": "/path/to/your/project"
      }
    }
  }
}

From source (development)

{
  "mcpServers": {
    "codereviewbuddy": {
      "command": "uv",
      "args": ["run", "--directory", "/path/to/codereviewbuddy", "codereviewbuddy"],
      "env": {
        "CRB_WORKSPACE": "/path/to/your/project"
      }
    }
  }
}

Troubleshooting

If your MCP client reports:

No module named 'fastmcp.server.tasks.routing'

that runtime is using an incompatible FastMCP environment.

Use one of these fixes:

1. Prefer uvx --prerelease=allow codereviewbuddy@latest in MCP client config.
2. For local source checkouts, launch with uv run --directory /path/to/codereviewbuddy codereviewbuddy.
3. Reinstall the tool to refresh cached deps: uv tool install --reinstall codereviewbuddy.

MCP Tools

Tool	Description
summarize_review_status	Lightweight stack-wide overview with severity counts — auto-discovers stack when pr_numbers omitted
list_review_comments	Fetch all review threads with reviewer ID, status, staleness, and auto-discovered stack field
list_stack_review_comments	Fetch comments for multiple PRs in a stack in one call, grouped by PR number
resolve_comment	Resolve a single inline thread by GraphQL node ID (PRRT_...)
resolve_stale_comments	Bulk-resolve threads on files modified since the review, with smart skip for auto-resolving reviewers
reply_to_comment	Reply to inline threads (PRRT_), PR-level reviews (PRR_), or bot comments (IC_)
request_rereview	Trigger re-reviews per reviewer (handles differences automatically)
create_issue_from_comment	Create a GitHub issue from a review comment with labels, PR backlink, and quoted text
review_pr_descriptions	Analyze PR descriptions across a stack for quality issues (empty body, boilerplate, missing linked issues)

Configuration

codereviewbuddy works zero-config with sensible defaults. All configuration is via CRB_* environment variables set in your MCP client config JSON — no config files needed.

Environment variables

Add env vars to the "env" block of your MCP client config:

{
  "mcpServers": {
    "codereviewbuddy": {
      "command": "uvx",
      "args": ["--prerelease=allow", "codereviewbuddy@latest"],
      "env": {
        "CRB_WORKSPACE": "/path/to/your/project",
        "CRB_SELF_IMPROVEMENT__ENABLED": "true",
        "CRB_SELF_IMPROVEMENT__REPO": "owner/codereviewbuddy",
        "CRB_DIAGNOSTICS__IO_TAP": "true"
      }
    }
  }
}

Nested settings use __ (double underscore) as a delimiter, following the same pattern as FastMCP's own FASTMCP_* env vars.

All settings

Env var	Type	Default	Description
CRB_WORKSPACE	string	(auto-detect)	Project directory for gh CLI — set this to avoid wrong-repo detection
CRB_PR_DESCRIPTIONS__ENABLED	bool	true	Whether review_pr_descriptions tool is available
CRB_SELF_IMPROVEMENT__ENABLED	bool	false	Agents file issues when they encounter server gaps
CRB_SELF_IMPROVEMENT__REPO	string	""	Repository to file issues against (e.g. owner/repo)
CRB_DIAGNOSTICS__IO_TAP	bool	false	Log stdin/stdout for transport debugging
CRB_DIAGNOSTICS__TOOL_CALL_HEARTBEAT	bool	false	Emit heartbeat entries for long-running tool calls
CRB_DIAGNOSTICS__HEARTBEAT_INTERVAL_MS	int	5000	Heartbeat cadence in milliseconds
CRB_DIAGNOSTICS__INCLUDE_ARGS_FINGERPRINT	bool	true	Log args hash/size in tool call logs

Severity levels

Each reviewer adapter classifies comments using its own format. Currently only Devin has a known severity format (emoji markers). Unblocked and CodeRabbit comments default to info until their formats are investigated.

Devin's emoji markers:

Emoji	Level	Meaning
🔴	bug	Critical issue, must fix before merge
🚩	flagged	Likely needs a code change
🟡	warning	Worth addressing but not blocking
📝	info	Informational, no action required
(none)	info	Default when no marker is present

Reviewers without a known format classify all comments as info. This means resolve_levels = ["info"] would allow resolving all their threads, while resolve_levels = [] blocks everything.

Resolve enforcement

The resolve_levels config is enforced server-side. If an agent tries to resolve a thread whose severity exceeds the allowed levels, the server returns an error. This prevents agents from resolving critical review comments regardless of their instructions.

For example, with the default config, resolving a 🔴 bug from Devin is blocked — only 📝 info threads can be resolved.

Reviewer behavior

Reviewer	Auto-reviews on push	Auto-resolves comments	Re-review trigger
Unblocked	No	No	request_rereview posts a configurable comment (default: "@unblocked please re-review")
Devin	Yes	Yes	Auto on push (no action needed)
CodeRabbit	Yes	Yes	Auto on push (no action needed)

Typical workflow

1. Push a fix
2. list_review_comments(pr_number=42)           # See all threads with staleness
3. resolve_stale_comments(pr_number=42)          # Batch-resolve changed files
4. reply_to_comment(42, thread_id, "Fixed in ...")  # Reply to remaining threads
5. request_rereview(pr_number=42)                # Trigger fresh review cycle

For stacked PRs, use list_stack_review_comments with all PR numbers to get a full picture before deciding what to fix.

Development

git clone https://github.com/detailobsessed/codereviewbuddy.git
cd codereviewbuddy
uv sync

Testing

poe test          # Run tests (excludes slow)
poe test-cov      # Run with coverage report
poe test-all      # Run all tests including slow

Quality checks

poe lint          # ruff check
poe typecheck     # ty check
poe check         # lint + typecheck
poe prek          # run all pre-commit hooks

Architecture

The server is built on FastMCP v3 with a clean separation:

• server.py — FastMCP server with tool registration, middleware, and instructions
• config.py — Per-reviewer configuration (CRB_* env vars via pydantic-settings, severity classifier, resolve policy)
• tools/ — Tool implementations (comments.py, stack.py, descriptions.py, issues.py, rereview.py)
• reviewers/ — Pluggable reviewer adapters with behavior flags (auto-resolve, re-review triggers)
• gh.py — Thin wrapper around the gh CLI for GraphQL and REST calls
• models.py — Pydantic models for typed tool outputs

All blocking gh CLI calls are wrapped with call_sync_fn_in_threadpool to avoid blocking the async event loop.

Template Updates

This project was generated with copier-uv-bleeding. To pull the latest template changes:

copier update --trust .