Exception: MCP::Server::MissingRequiredClientCapabilityError

Inherits:
RequestHandlerError show all
Defined in:
lib/mcp/server.rb

Overview

Raised when processing a request requires a client capability the request did not declare in _meta (io.modelcontextprotocol/clientCapabilities). Per SEP-2575, servers MUST NOT rely on capabilities the client has not declared. Maps to JSON-RPC error -32021 with data: { requiredCapabilities: {...} } listing the missing capabilities.

https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2575

Instance Attribute Summary

Attributes inherited from RequestHandlerError

#error_code, #error_data, #error_type, #original_error

Instance Method Summary collapse

Constructor Details

#initialize(required_capabilities, request = nil) ⇒ MissingRequiredClientCapabilityError

Returns a new instance of MissingRequiredClientCapabilityError.



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# File 'lib/mcp/server.rb', line 86

def initialize(required_capabilities, request = nil)
  super(
    "Missing required client capability",
    request,
    error_type: :missing_required_client_capability,
    error_code: ErrorCodes::MISSING_REQUIRED_CLIENT_CAPABILITY,
    error_data: { requiredCapabilities: required_capabilities },
  )
end