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-32601

Method Not Found

JSON-RPC 2.0

JSON-RPC method not found (-32601) means the requested method does not exist on this server. The server parsed the request correctly but has no handler for the method name. Common in MCP when calling capabilities the server did not declare in the initialize response.

Code

-32601

Decimal

-32601

Standard

JSON-RPC 2.0

Description

Method Not Found fires when the method string in the request does not match any method the server implements. In MCP, this typically means calling a method that requires a capability the server did not advertise during the initialize handshake. For example, calling resources/list on a server that advertised no resources capability in its initialize response should return -32601. Clients should check the server's capability map from initialize before calling optional methods.

Common Causes

  • Calling resources/list on a server that does not support resources
  • Calling prompts/get on a server that does not support prompts
  • Typo in method name (tools/call vs tools_call)
  • Calling a method before initialize completes
  • Calling a custom method the server does not implement