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Concurrent server-side sampling requests are serialized end-to-end

clientRelated to the FastMCP client SDK or client-side functionality.Related to the FastMCP client SDK or client-side functionality.

enhancementImprovement to existing functionality. For issues and smaller PR improvements.Improvement to existing functionality. For issues and smaller PR improvements.

Status: Open.

#4006 In PrefectHQ/fastmcp;

· demoray opened on Apr 21, 2026

ctx.set_state lacks custom TTL; no atomic consume_state

enhancementImprovement to existing functionality. For issues and smaller PR improvements.Improvement to existing functionality. For issues and smaller PR improvements.

serverRelated to FastMCP server implementation or server-side functionality.Related to FastMCP server implementation or server-side functionality.

too-longExcessively verbose or unedited LLM output. Condense before triage.Excessively verbose or unedited LLM output. Condense before triage.

Status: Open.

#4005 In PrefectHQ/fastmcp;

· pedrobacchini opened on Apr 21, 2026

FastMCP HTTP Stream Transport Fails with Auth0 SSO Behind AWS ALB

authRelated to authentication (Bearer, JWT, OAuth, WorkOS) for client or server.Related to authentication (Bearer, JWT, OAuth, WorkOS) for client or server.

bugSomething isn't working. Reports of errors, unexpected behavior, or broken functionality.Something isn't working. Reports of errors, unexpected behavior, or broken functionality.

httpRelated to HTTP transport, networking, or web server functionality.Related to HTTP transport, networking, or web server functionality.

Status: Open.

#4004 In PrefectHQ/fastmcp;

· sohail-norstella opened on Apr 21, 2026

Sync tool functions fail with Windows COM (CoInitialize not called) due to thread pool execution

enhancementImprovement to existing functionality. For issues and smaller PR improvements.Improvement to existing functionality. For issues and smaller PR improvements.

serverRelated to FastMCP server implementation or server-side functionality.Related to FastMCP server implementation or server-side functionality.

Status: Open.

#4003 In PrefectHQ/fastmcp;

· miloira opened on Apr 21, 2026

OpenTelemetry: FastMCP client does not propagate trace context on initialize and list methods

bugSomething isn't working. Reports of errors, unexpected behavior, or broken functionality.Something isn't working. Reports of errors, unexpected behavior, or broken functionality.

clientRelated to the FastMCP client SDK or client-side functionality.Related to the FastMCP client SDK or client-side functionality.

Status: Open.

#3998 In PrefectHQ/fastmcp;

· strawgate opened on Apr 21, 2026

FastMCPProxy servers trigger Claude Desktop's "Authentication required to use this tool" prompt on first tool call, plain FastMCP servers don't

authRelated to authentication (Bearer, JWT, OAuth, WorkOS) for client or server.Related to authentication (Bearer, JWT, OAuth, WorkOS) for client or server.

bugSomething isn't working. Reports of errors, unexpected behavior, or broken functionality.Something isn't working. Reports of errors, unexpected behavior, or broken functionality.

serverRelated to FastMCP server implementation or server-side functionality.Related to FastMCP server implementation or server-side functionality.

Status: Open.

#3996 In PrefectHQ/fastmcp;

· 7robots opened on Apr 20, 2026

feat: Add Azure AD B2C authentication provider

authRelated to authentication (Bearer, JWT, OAuth, WorkOS) for client or server.Related to authentication (Bearer, JWT, OAuth, WorkOS) for client or server.

enhancementImprovement to existing functionality. For issues and smaller PR improvements.Improvement to existing functionality. For issues and smaller PR improvements.

too-longExcessively verbose or unedited LLM output. Condense before triage.Excessively verbose or unedited LLM output. Condense before triage.

Status: Open.

#3994 In PrefectHQ/fastmcp;

· carlos-rian opened on Apr 20, 2026

Native telemetry breaks third-party OpenTelemetry instrumentations

bugSomething isn't working. Reports of errors, unexpected behavior, or broken functionality.Something isn't working. Reports of errors, unexpected behavior, or broken functionality.

clientRelated to the FastMCP client SDK or client-side functionality.Related to the FastMCP client SDK or client-side functionality.

serverRelated to FastMCP server implementation or server-side functionality.Related to FastMCP server implementation or server-side functionality.

Status: Open.

#3993 In PrefectHQ/fastmcp;

· adityamehra opened on Apr 20, 2026

Client._disconnect() needs timeout — hangs indefinitely on stale HTTP connections

bugSomething isn't working. Reports of errors, unexpected behavior, or broken functionality.Something isn't working. Reports of errors, unexpected behavior, or broken functionality.

clientRelated to the FastMCP client SDK or client-side functionality.Related to the FastMCP client SDK or client-side functionality.

httpRelated to HTTP transport, networking, or web server functionality.Related to HTTP transport, networking, or web server functionality.

needs MREBug reports require a copy/pastable MRE that can run as-is.Bug reports require a copy/pastable MRE that can run as-is.

too-longExcessively verbose or unedited LLM output. Condense before triage.Excessively verbose or unedited LLM output. Condense before triage.

Status: Open.

#3947 In PrefectHQ/fastmcp;

· godwinbw-egm opened on Apr 16, 2026

OTEL: Instrument ctx.sample() / sampling loop with spans and metrics

too-longExcessively verbose or unedited LLM output. Condense before triage.Excessively verbose or unedited LLM output. Condense before triage.

Status: Open.

#3891 In PrefectHQ/fastmcp;

· strawgate opened on Apr 13, 2026

Docs: Best practices for emitting custom spans from tools, prompts, and resources

documentationUpdates to docs, examples, or guides. Primary change is documentation-related.Updates to docs, examples, or guides. Primary change is documentation-related.

Status: Open.

#3888 In PrefectHQ/fastmcp;

· strawgate opened on Apr 13, 2026

OTEL: Instrument all MCP methods, not just tools/call, resources/read, prompts/get

clientRelated to the FastMCP client SDK or client-side functionality.Related to the FastMCP client SDK or client-side functionality.

enhancementImprovement to existing functionality. For issues and smaller PR improvements.Improvement to existing functionality. For issues and smaller PR improvements.

serverRelated to FastMCP server implementation or server-side functionality.Related to FastMCP server implementation or server-side functionality.

Status: Open.

#3887 In PrefectHQ/fastmcp;

· strawgate opened on Apr 13, 2026