rate_limiting

fastmcp.server.middleware.rate_limiting

Rate limiting middleware for protecting FastMCP servers from abuse.

Classes

RateLimitError

Error raised when rate limit is exceeded.

TokenBucketRateLimiter

Token bucket implementation for rate limiting.

Methods:

consume

consume(self, tokens: int = 1) -> bool

Try to consume tokens from the bucket.

Args:

• tokens: Number of tokens to consume

Returns:

• True if tokens were available and consumed, False otherwise

SlidingWindowRateLimiter

Sliding window rate limiter implementation.

Methods:

is_allowed

is_allowed(self) -> bool

Check if a request is allowed.

RateLimitingMiddleware

Middleware that implements rate limiting to prevent server abuse.

Uses a token bucket algorithm by default, allowing for burst traffic while maintaining a sustainable long-term rate.

Methods:

on_request

on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any

Apply rate limiting to requests.

SlidingWindowRateLimitingMiddleware

Middleware that implements sliding window rate limiting.

Uses a sliding window approach which provides more precise rate limiting but uses more memory to track individual request timestamps.

Methods:

on_request

on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any

Apply sliding window rate limiting to requests.