Dev MCP Builder

dev/mcp-builder — skill payload

Machine-readable contract: ../mcp-builder.manifest.json.

What this skill does

Scaffolds a FastMCP Python MCP server from a tool-list spec. Generated files include:

• server.py with FastMCP(name=...) and one @mcp.tool stub per declared tool, wired for both stdio and streamable-http transports via an MCP_TRANSPORT env var.
• requirements.txt pinning fastmcp and friends.
• Dockerfile with the standard uvicorn entry point for HTTP transport.
• tests/test_server.py with one passing smoke test per tool.

When to use it

• You're standing up a new MCP server from scratch.
• A new skill needs its own endpoint (one MCP host per plugin — see the Cowork limitations doc) and you want a starter that already passes the smoke tests in this repo.

When not to use it

• You're adding a tool to an existing MCP server — edit the existing server.py directly.
• Your target is a non-Python MCP server (TypeScript, Go) — this skill only emits Python.

Determinism and risk

Determinism: medium — file paths are deterministic; comments and docstrings vary slightly. Risk: low — generated files are reviewable before commit.

How it composes

Often paired with dev/skill-creator for end-to-end "new capability → new server" bootstrapping, and dev/webapp-testing for the post-deploy verification step.