v2.14.0: Task and You Shall Receive

FastMCP 2.14 begins adopting the MCP 2025-11-25 specification, headlined by protocol-native background tasks that let long-running operations report progress without blocking clients. This release also graduates the OpenAPI parser to standard, adds first-class support for several new spec features, and removes deprecated APIs accumulated across the 2.x series.

Background Tasks (SEP-1686)

Long-running operations (like tool calls) normally block MCP clients until they complete. The new MCP background task protocol (SEP-1686) lets clients start operations, track progress, and retrieve results without blocking. For FastMCP users, taking advantage of this new functionality is as easy as adding task=True to any async decorator. Under the hood, it's powered by Docket, the enterprise task scheduler at the heart of Prefect Cloud that handles millions of concurrent tasks every day.

from fastmcp import FastMCP
from fastmcp.dependencies import Progress
mcp = FastMCP("MyServer")
@​mcp.tool(task=True)
async def train_model(dataset: str, progress: Progress = Progress()) -> str:
await progress.set_total(100)
for epoch in range(100):
# ... training work ...
await progress.increment()
return "Model trained successfully"

Clients that call this tool in task-augmented mode (for FastMCP clients, that merely means another task=True!) receive a task ID immediately, poll for progress updates, and fetch results when ready. Background tasks work out-of-the-box with an in-memory backend, and users can optionally provide a Redis URL for persistence, horizontal scaling, and single-digit millisecond task pickup latency. When using Redis, users can also add additional Docket workers to scale out their task processing.

Read the docs here!

OpenAPI Parser Promotion

The experimental OpenAPI parser graduates to standard. The new architecture delivers improved performance through single-pass schema processing and cleaner internal abstractions. Existing code works unchanged; users of the experimental module should update their imports.

MCP 2025-11-25 Spec Support

This release begins adopting the MCP 2025-11-25 specification. Beyond the core SDK updates, FastMCP adds first-class developer experiences for:

• SEP-1686: Background tasks with progress tracking
• SEP-1699: SSE polling and event resumability, with full AsyncKeyValue support
• SEP-1330: Multi-select enum elicitation schemas
• SEP-1034: Default values for elicitation schemas
• SEP-986: Tool name validation at registration time

As the MCP SDK continues to adopt more of the specification, FastMCP will add corresponding high-level APIs.

Breaking Changes & Cleanup

This release removes deprecated APIs accumulated across the 2.x series: BearerAuthProvider, Context.get_http_request(), the dependencies parameter, legacy resource prefix formats, and several deprecated methods. The upgrade guide provides migration paths for each.

What's Changed