Issues

• Proxies drop prompt argument titles, and PromptArgument cannot set one

  buglow-priorityserver
  PrefectHQ/fastmcp#5748 · Filter by author AarnavNoble opened on Oct 15, 2026

• Proxy's sampling relay replaces the client's model, stop reason and non-text content

  bugserver
  PrefectHQ/fastmcp#5746 · Filter by author AarnavNoble opened on Oct 15, 2026

• Unregistered-client HTML error page discards the registration and discovery endpoints

  authbug
  PrefectHQ/fastmcp#5744 · Filter by author D41910 opened on Oct 15, 2026

• Sync tool keeps running after its timeout fires (follow-up to #5379)

  enhancementserver
  PrefectHQ/fastmcp#5743 · Filter by author harshithv281 opened on Oct 14, 2026
  1

• Sync resource templates run on the event loop and block other requests

  bugserver
  PrefectHQ/fastmcp#5741 · Filter by author hardness1020 opened on Oct 14, 2026

• from_openapi: a $ref into a component's property resolves to the wrong schema

  bugopenapi
  PrefectHQ/fastmcp#5739 · Filter by author AarnavNoble opened on Oct 14, 2026

• Declared schema defaults stay unhydrated with additionalProperties: true

  bugserver
  PrefectHQ/fastmcp#5737 · Filter by author Vittuu opened on Oct 13, 2026

• x-unsupported-pattern is dropped when a string schema sets a format

  buglow-priority
  PrefectHQ/fastmcp#5729 · Filter by author gdut4140 opened on Oct 13, 2026

• @mcp.tool(task=True) rejects an async-generator tool as a "sync function"

  bugtaskstoo-long
  PrefectHQ/fastmcp#5728 · Filter by author gdut4140 opened on Oct 13, 2026
  1

• LoggingMiddleware(methods=[]) logs every message instead of none

  bugserver
  PrefectHQ/fastmcp#5726 · Filter by author gdut4140 opened on Oct 13, 2026

• Retrieve a ToolTask by task ID in a new client session

  clientenhancementtasks
  PrefectHQ/fastmcp#5722 · Filter by author WilliamQue opened on Oct 13, 2026
  1

• Client.call_tool(name, version=...) validates the result against the highest version's output schema

  bugclient
  PrefectHQ/fastmcp#5721 · Filter by author gdut4140 opened on Oct 13, 2026
  1

• Doc Termination String Bug in v4 (not present in v3)

  bugserver
  PrefectHQ/fastmcp#5720 · Filter by author ptrailblazer89 opened on Oct 13, 2026

• Pluggable Semantic and Model-Based Tool Discovery

  enhancementproposalservertoo-long
  PrefectHQ/fastmcp#5719 · Filter by author riccardoferrara opened on Oct 13, 2026
  1

• OAuthProxy default FileTreeStore is never culled, expired OAuth state fills the volume

  authbug
  PrefectHQ/fastmcp#5718 · Filter by author mheidari98 opened on Oct 13, 2026

• Feature/Fix: Support server-level description in FastMCP to prevent routing bias under lazy loading hosts

  needs more infoserver
  PrefectHQ/fastmcp#5717 · Filter by author xujiawen8610 opened on Oct 13, 2026

• Upgrade checks failing on main branch

  build failed
  PrefectHQ/fastmcp#5714 · Filter by author github-actions opened on Oct 13, 2026
  2

• Code Mode Search: default_limit=None documented as "no limit" but silently caps results at 50; per-call limit above 50 is also capped

  bug
  PrefectHQ/fastmcp#5712 · Filter by author BlueX888 opened on Oct 12, 2026

• list_resources/list_resource_templates/list_prompts dispatch middleware with message={} while list_tools sends a typed request model

  bugserver
  PrefectHQ/fastmcp#5710 · Filter by author BlueX888 opened on Oct 12, 2026
  1

• from_openapi: a media-type schema's own $defs are dropped from the tool schema when components/schemas is non-empty

  bugopenapi
  PrefectHQ/fastmcp#5708 · Filter by author BlueX888 opened on Oct 12, 2026
  1

• Resource template with a level-3 operator such as {&size} is listed but can never be read

  bug
  PrefectHQ/fastmcp#5706 · Filter by author chrikrah opened on Oct 12, 2026

• Client.read_resource cannot read advertised namespaced file resources

  bugserver
  PrefectHQ/fastmcp#5705 · Filter by author BlueLi66 opened on Oct 12, 2026
  1

• Transformed tools lose their icons

  bugserver
  PrefectHQ/fastmcp#5687 · Filter by author asasemahmed opened on Oct 12, 2026

• fastmcp inspect crashes or drops text when server metadata contains square brackets

  bugcli
  PrefectHQ/fastmcp#5686 · Filter by author asasemahmed opened on Oct 12, 2026

• fastmcp run fails with FileNotFoundError when fastmcp.json sets deployment.cwd

  bugclifastmcp.json
  PrefectHQ/fastmcp#5685 · Filter by author asasemahmed opened on Oct 12, 2026