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: 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: @mcp . resource ( "data://config" ) def get_config ( ) -

dict : """Return server configuration""" return { "version" : "1.0" , "debug" : False } Create a resource template: @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: @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: if name == "main" : mcp . run ( )

Or with transport options:

mcp.run(transport="sse", host="0.0.0.0", port=8000)

Using context in tools 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 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