mcp-lint

A production-quality linter for MCP (Model Context Protocol) servers

mcp-lint connects to any MCP server via stdio or SSE transport, runs 23 deterministic lint rules across 4 categories, and outputs a scored report with CI/CD-friendly exit codes.

No LLM required. No API keys. Pure static analysis of your MCP server's protocol behavior.

Features

• 23 lint rules across 4 categories: Protocol, Schema, Security, Performance
• Multiple transports — stdio and SSE support
• CI/CD ready — --fail-under flag with exit codes (0 = pass, 1 = below threshold, 2 = error)
• 3 output formats — terminal (Rich), JSON, Markdown
• Rule filtering — --include / --exclude specific rules
• Zero configuration — works out of the box with sensible defaults

Installation

pip install mcp-lint

Quick Start

# Lint an MCP server via stdio
mcp-lint "python -m your_mcp_server"

# Lint via SSE
mcp-lint --url http://localhost:8000/sse

# JSON output for CI pipelines
mcp-lint "python -m your_mcp_server" --format json

# Fail CI if score drops below 80%
mcp-lint "python -m your_mcp_server" --fail-under 80

# Verbose output with details
mcp-lint "python -m your_mcp_server" -v

Lint Rules

Protocol (6 rules)

Schema (5 rules)

Security (8 rules)

Performance (4 rules)

CLI Reference

Usage: mcp-lint [OPTIONS] [COMMAND]

Arguments:
  COMMAND    MCP server command to run (stdio transport)

Options:
  --url TEXT               MCP server SSE URL
  -f, --format FORMAT      Output: terminal, json, markdown (default: terminal)
  --fail-under FLOAT       Exit 1 if score < threshold (default: 0)
  --timeout FLOAT          Global timeout in seconds (default: 30)
  --include TEXT            Comma-separated rule IDs to include
  --exclude TEXT            Comma-separated rule IDs to exclude
  -v, --verbose            Show detailed output
  -V, --version            Show version and exit

Scoring

Each rule produces a result: PASS (1.0), WARN (0.5), FAIL (0.0), or SKIP (excluded from scoring).

The overall score is the weighted average as a percentage, mapped to a letter grade:

CI/CD Integration

GitHub Actions

- name: Lint MCP Server
  run: |
    pip install mcp-lint
    mcp-lint "python -m my_server" --fail-under 80 --format json

Exit Codes

Development

git clone https://github.com/Luxshan2000/mcp-lint.git
cd mcp-lint
make dev        # install in editable mode
make test       # run tests
make lint       # run ruff linter
make format     # format code
make check      # lint + format check + tests

License

MIT