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Transforms reshape what clients see in list responses — renaming, filtering, namespacing — without touching the underlying registrations. Components hidden by a transform are removed from lists but remain callable by their original name or URI. Register with server.transform(t) or via FastMCPOptions.transforms; transforms apply in registration order.
This page is under construction. The outline below sketches what it will cover.
  • View types — read-only ToolView / ResourceView / PromptView snapshots passed into transform methods; returning null hides a component.
  • Built-ins — renameTool, redescribeTool, FilterTransform, NamespaceTransform(prefix) (prefixes names but never URIs — prefixing a URI scheme violates RFC 3986), ResourcesAsTools(), PromptsAsTools(), VersionFilter(tag).
  • Synthesized tools — synthesizeTools(resourceViews, promptViews) produces new tools from filtered views; synthesized tools run back through the transform chain.
  • Routing behavior with transforms active — how tools/call, prompts/get, and resources/read resolve transformed vs. original names.