fastmcp

v3.3.1 Bugfix

This release fixes issues for SREs watching stability and regressions.

Published 19d AI Coding Tools

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✓ No known CVEs patched

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✓ No known CVEs patched in this version

Topics

agents fastmcp llms mcp mcp-clients mcp-servers

+3 more

mcp-tools model-context-protocol python

Summary

AI summary

Decoupled component imports to prevent circular import failures during clean installs of FastMCP 3.3.0.

Changes in this release

Type	Severity	Summary	CVE
Feature	Low	Preserves old server import paths as compatibility re-exports. Preserves old server import paths as compatibility re-exports. Source: granite4.1:30b@2026-05-22-audit Confidence: high	—
Bugfix	Medium	Fixes clean install failures on standalone component imports in FastMCP 3.3.0. Fixes clean install failures on standalone component imports in FastMCP 3.3.0. Source: llm_adapter@2026-05-21 Confidence: high	—
Refactor	Low	Decouples component auth and task primitives from server module. Decouples component auth and task primitives from server module. Source: granite4.1:30b@2026-05-22-audit Confidence: high	—
Other	Medium	Corrects documentation issues from the 3.3 rollout. Corrects documentation issues from the 3.3 rollout. Source: llm_adapter@2026-05-21 Confidence: low	—

Full changelog

FastMCP 3.3.1 is a hotfix for the 3.3 packaging split. Clean installs of 3.3.0 could fail on standalone component imports like from fastmcp.tools import tool because component modules reached auth and task primitives through fastmcp.server, pulling in the server/provider stack and exposing a circular import.

Component-level auth and task primitives now live in lightweight utility modules, with the old server import paths preserved as compatibility re-exports. Component imports stay lightweight, existing server-facing imports continue to work, and the release also includes small docs corrections from the 3.3 rollout.

What's Changed

Fixes 🐞

fix(docs): use valid FA icon on client-only package page by @jlowin in https://github.com/PrefectHQ/fastmcp/pull/4139
Decouple component imports from server by @jlowin in https://github.com/PrefectHQ/fastmcp/pull/4150

Full Changelog: https://github.com/PrefectHQ/fastmcp/compare/v3.3.0...v3.3.1

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