Installation and extras

The package is fastmcp-feedback on PyPI. It needs Python 3.11 or newer and FastMCP 2.12.2 or newer, below 5.

uv add fastmcp-feedback                                      # base
uv add "fastmcp-feedback[instrumentation]"                   # + DatabaseSink
uv add "fastmcp-feedback[instrumentation,embeddings]" asyncpg  # + embeddings on Postgres

What each install covers

Install	Adds	Covers
fastmcp-feedback	fastmcp>=2.12.2,<5, sqlalchemy>=2.0.43, pydantic>=2.11.7	The five feedback tools (sync SQLAlchemy). instrument(app) with JsonLinesSink, CallbackSink and MemorySink; events; redaction; result classification
[instrumentation]	sqlalchemy[asyncio] (brings greenlet), aiosqlite	DatabaseSink, build_metadata, feedback linking across workers and restarts (capture_recent_calls, link_feedback, feedback_context), events_for from the database
[instrumentation,embeddings]	pgvector>=0.5.0	EmbeddingSink, OpenAIEmbedder, similar(), similar_feedback(), the backfill API and CLI
[postgresql]	psycopg2-binary	The feedback tools on PostgreSQL (postgresql:// URLs)
[mysql]	pymysql	A driver for the feedback tools on MySQL (mysql+pymysql://); the test suite does not cover MySQL

Drivers

The instrumentation’s database code is async; the feedback tools’ is sync. They use different drivers and URL schemes:

Store	Async URL (DatabaseSink, backfill)	Sync URL (add_feedback_tools)
SQLite	sqlite+aiosqlite:///calls.db (in [instrumentation])	sqlite:///feedback.db
PostgreSQL	postgresql+asyncpg://... (add asyncpg)	postgresql://... ([postgresql] extra)

pgvector is only needed when embeddings are stored on PostgreSQL. On SQLite, vectors are stored as JSON lists.

Missing extras

Without the instrumentation extra, importing DatabaseSink (or any other name that needs the async database stack) raises an ImportError that names the missing package and the extra to install:

ImportError: fastmcp_feedback.instrumentation.DatabaseSink needs the async database stack, and greenlet is not installed. Install it with: uv add "fastmcp-feedback[instrumentation]" (or pip install "fastmcp-feedback[instrumentation]")

The middleware’s database helpers (capture_recent_calls, feedback_context, events_for, similar, …) then return their empty results instead of raising.

Versions

Releases use calendar versioning, YYYY.MM.DD, with .1, .2 for further releases the same day. PyPI normalizes leading zeros, so 2026.10.01.2 and 2026.10.1.2 are the same version. Changes are listed in the changelog.