fastmcp-server

# FastMCP 3.0 Server Development Complete reference for building production-ready MCP (Model Context Protocol) servers with FastMCP 3.0 - the fast, Pythonic framework for connecting LLMs to tools and data. ## When to use this skill **Use FastMCP Server when:** - Creating a new MCP server in Python - Adding tools, resources, or prompts to an MCP server - Implementing authentication (OAuth, OIDC, token verification) - Setting up middleware for logging, rate limiting, or authorization - Configuring providers (local, filesystem, skills, custom) - Building production MCP servers with telemetry and storage - Upgrading from FastMCP 2.x to 3.0 **Key areas covered:** - **Tools & Resources** (CORE): Decorators, validation, return types, templates - **Context & DI** (CORE): MCP context, dependency injection, background tasks - **Authentication** (SECURITY): OAuth, OIDC, token verification, proxy patterns - **Authorization** (SECURITY): Scope-based and role-based access control - **Middleware** (ADVANCED): Request/response pipeline, built-in middleware - **Providers** (ADVANCED): Local, filesystem, skills, and custom providers - **Features** (ADVANCED): Pagination, sampling, storage, OpenTelemetry, versioning ## Quick reference ### Core patterns **Create a server with tools:** ```python from fastmcp import FastMCP mcp = FastMCP("MyServer") @mcp.tool def add(a: int, b: int) -> int: """Add two numbers""" return a + b ``` **Create a resource:** ```python @mcp.resource("data://config") def get_config() -> dict: """Return server configuration""" return {"version": "1.0", "debug": False} ``` **Create a resource template:** ```python @mcp.resource("users://{user_id}/profile") def get_user_profile(user_id: str) -> dict: """Get a user's profile by ID""" return fetch_user(user_id) ``` **Create a prompt:** ```python @mcp.prompt def review_code(code: str, language: str = "python") -> str: """Review code for best practices""" return f"Review this {language} code:\n\n{code}" ``` **Run the server:** ```python if __name__ == "__main__": mcp.run() # Or with transport options: # mcp.run(transport="sse", host="0.0.0.0", port=8000) ``` ### Using context in tools ```python from fastmcp import FastMCP, Context mcp = FastMCP("MyServer") @mcp.tool def process_data(uri: str, ctx: Context) -> str: """Process data with logging and progress""" ctx.info(f"Processing {uri}") ctx.report_progress(0, 100) data = ctx.read_resource(uri) ctx.report_progress(100, 100) return f"Processed: {data}" ``` ### Authentication setup ```python from fastmcp import FastMCP from fastmcp.server.auth import BearerAuthProvider auth = BearerAuthProvider( jwks_uri="https://your-provider/.well-known/jwks.json", audience="your-api", issuer="https://your-provider/" ) mcp = FastMCP("SecureServer", auth=auth) ``` ## Key concepts ### Tools Functions exposed as executable capabilities for LLMs. Decorated with `@mcp.tool`. Support Pydantic validation, async, custom return types, and annotations (readOnlyHint, destructiveHint). ### Resources & Templates Static or dynamic data sources identified by URIs. Resources use fixed URIs (`data://config`), templates use parameterized URIs (`users://{id}/profile`). Support MIME types, annotations, and wildcard parameters. ### Context The `Context` object provides access to MCP features within tools/resources: logging, progress reporting, resource access, LLM sampling, user elicitation, and session state. ### Dependency Injection Inject values into tool/resource functions using `Depends()`. Supports HTTP requests, access tokens, custom dependencies, and generator-based cleanup patterns. ### Providers Control where components come from. `LocalProvider` (default, decorator-based), `FileSystemProvider` (load from Python files on disk), `SkillsProvider` (packaged bundles), or custom providers. ### Authentication & Authorization Multiple auth patterns: token verification (JWT, JWKS), OAuth proxy, OIDC proxy, remote OAuth, and full OAuth server. Authorization via scopes on components and middleware. ### Middleware Intercept and modify requests/responses. Built-in middleware for rate limiting, error handling, logging, and response size limits. Custom middleware via `@mcp.middleware`. ## Using the references Detailed documentation is organized in the `references/` folder: ### Getting Started - **getting-started/installation.md** - Install FastMCP, optional dependencies, verify setup - **getting-started/upgrade-guide.md** - Migrate from FastMCP 2.x to 3.0 - **getting-started/quickstart.md** - First server, tools, resources, prompts, running ### Server - **server/server-class.md** - FastMCP server configuration, transport options, tag filtering - **server/tools.md** - Tool decorator, parameters, validation, return types, annotations - **server/resources-and-templates.md** - Resources, templates, URIs, wildcards, MIME types ### Context - **context/mcp-context.md** - Context object, logging, progress, resource access, sampling - **context/background-tasks.md** - Long-running operations with task support - **context/dependency-injection.md** - Depends(), custom deps, HTTP request, access tokens - **context/user-elicitation.md** - Request structured input from users during execution ### Features - **features/icons.md** - Custom icons for tools, resources, prompts, and servers - **features/lifespans.md** - Server lifecycle management and startup/shutdown hooks - **features/client-logging.md** - Send log messages to MCP clients - **features/middleware.md** - Request/response pipeline, built-in and custom middleware - **features/pagination.md** - Paginate large component lists - **features/progress-reporting.md** - Report progress for long-running operations - **features/sampling.md** - Request LLM completions from the client - **features/storage-backends.md** - Memory, file, and Redis storage for caching and tokens - **features/opentelemetry.md** - Distributed tracing and observability - **features/versioning.md** - Version components and filter by version ranges ### Authentication - **authentication/token-verification.md** - JWT, JWKS, introspection, static keys, custom - **authentication/remote-oauth.md** - Delegate auth to upstream OAuth provider - **authentication/oauth-proxy.md** - Full OAuth proxy with PKCE, client management - **authentication/oidc-proxy.md** - OpenID Connect proxy with auto-discovery - **authentication/full-oauth-server.md** - Complete built-in OAuth server ### Authorization - **authorization.md** - Scope-based access control, middleware authorization, patterns ### Providers - **providers/local.md** - Default provider, decorator-based component registration - **providers/filesystem.md** - Load components from Python files on disk - **providers/skills.md** - Package and distribute component bundles - **providers/custom.md** - Build custom providers for any component source ## Version history **v1.0.0** (February 2026) - Initial release covering FastMCP 3.0 (release candidate) - 30 reference files across 7 categories - Complete coverage of tools, resources, context, auth, providers, and features --- > Converted and distributed by [TomeVault](https://tomevault.io) | [Claim this content](https://tomevault.io/claim/davila7/claude-code-templates) <!-- tomevault:2.0:skill_md:2026-04-05 -->