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Everything Server - Extension Points

Architecture | Project Structure | Startup Process | Server Features | Extension Points | How It Works

Adding Tools

Create a new file under tools/ with your registerXTool(server) function that registers the tool via server.registerTool(...). Take the context (server/context.ts) as a second argument if the tool needs the protocol era, the change publisher, or state that lives as long as the connection.
Export and call it from tools/index.ts, in the function for the eras that get it: registerTools(server, context) for both, registerModernTools for 2026-07-28 only, registerLegacyTools or registerConditionalTools (capability-gated) for the 2025 era only.
Never keep state in a module-level map keyed by session id: the 2026-07-28 protocol has no sessions, and its HTTP path builds a fresh server per request. Keep per-connection state in the registration closure, and state that must outlive a request under a handle the server mints (as server/tasks.ts and resources/minted.ts do).
For client input (elicitation, sampling, roots), return inputRequired(...) from the handler rather than sending a request; the SDK's legacy shim serves the same handler to 2025-era clients.

Adding Prompts

Create a new file under prompts/ with your registerXPrompt(server) function that registers the prompt via server.registerPrompt(...).
Export and call it from prompts/index.ts inside registerPrompts(server).

Adding Resources

Create a new file under resources/ with your registerXResources(server) function using server.registerResource(...) (optionally with ResourceTemplate).
Export and call it from resources/index.ts inside registerResources(server, context).