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. Same shape as cofferdam invariants show --robot, which reports rather more: which files were read, and which of them the layers in force actually came from.

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.

cofferdam context has no MCP tool yet, so an agent working over MCP alone cannot fetch the digest that the recommended workflow opens with. Until it lands, call the CLI for that one step and MCP for the rest.