Crate fastmcp_server 

MCP server implementation for FastMCP.

This crate provides the server-side implementation:

• Server builder pattern
• Tool, resource, and prompt registration
• Request routing and dispatching
• Session management

Example

use fastmcp_rust::prelude::*;

#[tool]
async fn greet(ctx: &McpContext, name: String) -> String {
    format!("Hello, {name}!")
}

fn main() {
    Server::new("my-server", "1.0.0")
        .tool(greet)
        .run_stdio();
}

Role in the System

fastmcp-server is the execution engine for MCP servers. It ties together:

• Protocol types (fastmcp-protocol) for requests and responses
• Transports (fastmcp-transport) for stdio/SSE/WebSocket I/O
• Core context + cancellation (fastmcp-core) for budgets and checkpoints
• Console output (fastmcp-console) for human-friendly stderr rendering

The façade crate fastmcp re-exports this API, so most users interact with Server via fastmcp_rust::prelude::*.

Re-exports

pub use bidirectional::PendingRequests;

pub use bidirectional::RequestSender;

pub use bidirectional::TransportElicitationSender;

pub use bidirectional::TransportRootsProvider;

pub use bidirectional::TransportSamplingSender;

Modules

bidirectional

Bidirectional request handling for server-to-client communication.

caching

Response caching middleware for MCP servers.

docket

Docket: Distributed task queue for FastMCP.

oauth

OAuth 2.0/2.1 Authorization Server for MCP.

oidc

OpenID Connect (OIDC) Provider for MCP.

providers

Built-in resource providers for common use cases.

rate_limiting

Rate limiting middleware for protecting FastMCP servers from abuse.

transform

Tool transformations for dynamic schema modification.

Structs

AllowAllAuthProvider

Default allow-all provider (returns anonymous auth context).

AuthRequest

Authentication request view used by providers.

BidirectionalSenders

Configuration for bidirectional senders to attach to context.

ConsoleConfig

Comprehensive configuration for FastMCP console output

LifespanHooks

Lifecycle hooks for server startup and shutdown.

LoggingConfig

Logging configuration for the server.

MountResult

Result of a mount operation.

ProgressNotificationSender

A notification sender that sends progress notifications via a callback.

ProxyCatalog

Catalog of remote definitions used to register proxy handlers.

ProxyClient

Shared proxy client wrapper for handler reuse.

Router

Routes MCP requests to the appropriate handlers.

RouterResourceReader

A wrapper that implements ResourceReader for a shared Router.

RouterToolCaller

A wrapper that implements ToolCaller for a shared Router.

Server

An MCP server instance.

ServerBuilder

Builder for configuring an MCP server.

ServerStats

Thread-safe server statistics collector.

Session

An MCP session between client and server.

StaticTokenVerifier

Static token verifier backed by an in-memory token map.

StatsSnapshot

Point-in-time snapshot of server statistics.

TagFilters

Tag filtering parameters for list operations.

TaskManager

Background task manager.

TokenAuthProvider

Token-based authentication provider.

Enums

BannerStyle

Style variants for the startup banner

DuplicateBehavior

Behavior when registering a component with a name that already exists.

MiddlewareDecision

Result of middleware request interception.

TrafficVerbosity

Verbosity levels for traffic logging

Traits

AuthProvider

Authentication provider interface.

Middleware

Middleware hook trait for request/response interception.

PromptHandler

Handler for a prompt.

ProxyBackend

Backend interface used by proxy handlers.

ResourceHandler

Handler for a resource.

TokenVerifier

Token verifier interface used by token-based auth providers.

ToolHandler

Handler for a tool.

Functions

create_context_with_progress

Helper to create an McpContext with optional progress reporting and session state.

create_context_with_progress_and_senders

Helper to create an McpContext with optional progress reporting, session state, and bidirectional senders.

Type Aliases

BoxFuture

A boxed future for async handler results.

NotificationSender

Type alias for a notification sender callback.

SharedTaskManager

Thread-safe handle to a TaskManager.

ShutdownHook

Type alias for shutdown hook function.

StartupHook

Type alias for startup hook function.