FastMCP Builder Template

A local-first FastMCP v3 starter template for building, reviewing, and teaching MCP server design. It gives Claude Code a project-scoped MCP server with tools, resources, prompts, skills, and explicit slash-command workflows.

Prerequisites

• Python 3.11+
• uv (package manager)

Quick Start

uv sync
uv run fastmcp version

Run the server locally with STDIO:

uv run fastmcp run src/fastmcp_builder/server.py:mcp

Claude Code can discover this project server from the root .mcp.json.

Using With Claude Code

Open Claude Code from the repository root after installing dependencies:

uv sync
claude

The root .mcp.json configures a project-scoped MCP server named fastmcp-builder:

uv run fastmcp run src/fastmcp_builder/server.py:mcp

In Claude Code, run:

/mcp

Expected result: fastmcp-builder appears as a project-scoped MCP server. Claude can then use the builder tools, resources, and prompts from this repository while working on the project.

You can also use this repo as a cross-project MCP advisor by pointing another project's .mcp.json at this server with uv --directory; see docs/claude-code-workflow.md.

What This Template Teaches

• Tools are model-controlled capabilities.
• Resources are client/app-controlled data.
• Prompts are user-triggered workflows.
• FastMCP v3 exposes those primitives with @mcp.tool, @mcp.resource, and @mcp.prompt.

Included Builder Capabilities

Tools

• Classify whether a use case should be a tool, resource, or prompt.
• Review a capability manifest for deterministic design findings.
• Suggest tool, resource, and prompt contracts.
• Generate a minimal FastMCP server implementation plan.
• Check tool and prompt name format (snake_case, length, generic name validation).
• Check resource URI stability (volatile tokens, query strings, live HTTP URLs).
• Check tool description quality for model-controlled use.
• Classify tool failure modes into validation, transient, permission, and business errors.
• Expose local docs and examples as MCP resources.

Project-Scoped Skills

Invoke these from Claude Code with the listed slash command:

Skill	Command	Purpose
mcp-primitive-classification	/mcp-primitive-classification	Decide tool vs resource vs prompt
fastmcp-design-review	/fastmcp-design-review	Review an existing or proposed server
fastmcp-scaffold-author	/fastmcp-scaffold-author	Create a new FastMCP server from scratch
fastmcp-build-loop	/fastmcp-build-loop	Add tools/resources/prompts from a spec file

Learning Docs

Available as MCP resources at fastmcp-builder://docs/{slug}:

• mcp-primitives — tool vs resource vs prompt decision guide
• tool-design — tool contract patterns
• resource-design — resource URI and read-behavior patterns
• prompt-design — reusable workflow prompt patterns
• fastmcp-patterns — common FastMCP v3 code patterns
• safety-boundaries — local-first boundaries and what to exclude
• claude-code-workflow — explore → plan → implement → verify workflow
• raw-mcp-to-fastmcp-v3 — translating raw MCP SDK code to standalone FastMCP v3

Local Boundaries

This template intentionally excludes runtime network calls, arbitrary shell execution, databases, auth, hosted UIs, crawlers, scrapers, and background jobs.

Contributing

See CONTRIBUTING.md for development setup, scope rules, and PR guidelines.