MCP server

cofferdam-mcp is a minimal Model Context Protocol stdio server exposing five tools, all thin wrappers over the same library functions the cofferdam CLI calls — CLI and MCP output are byte-for-byte identical:

• cofferdam.check — given a filesystem path (file or directory), runs cofferdam's built-in checks against it and returns findings as JSON (the same schema cofferdam check --robot produces).
• cofferdam.advise — static, per-file architectural advisory (layer membership, public-API status, and the rule constraints that apply) without running the engine. Same JSON shape as cofferdam advise --format=json.
• cofferdam.advise_diff — pre-flight check: diffs findings between a git ref and the working tree, returning would_fire / would_clear sets. Same shape as cofferdam advise --diff <ref>.
• cofferdam.explain — a check's metadata and prose explanation by ID (built-in or plugin-declared). Same shape as cofferdam explain <id> --robot.
• cofferdam.invariants — the parsed cofferdam.invariants.toml (layers, public_api, boundaries, invariants) as JSON, discovered upward from a given path. No CLI equivalent exists — this is MCP-only.

All five load cofferdam.toml / cofferdam.invariants.toml when discoverable upward from the target path, otherwise run with default options.

Build the binary with cargo build --release -p cofferdam-mcp; the executable lands at target/release/cofferdam-mcp (.exe on Windows).

Example client config

{
  "mcpServers": {
    "cofferdam": {
      "command": "/absolute/path/to/target/release/cofferdam-mcp"
    }
  }
}

This is the shape used by Claude Desktop's claude_desktop_config.json and Claude Code's stdio MCP server config; point command at your built binary.

Scope

No HTTP/SSE transport, no auth, no streaming, no caching — stdio only, stateless.