A JSON-RPC error indicating that the method parameters are invalid or malformed. In MCP, this error is returned in various contexts when request parameters fail validation: - Tools: Unknown tool name or invalid tool arguments
- Prompts: Unknown prompt name or missing required arguments
- Pagination: Invalid or expired cursor values
- Logging: Invalid log level
- Elicitation: Server requests an elicitation mode not declared in client capabilities
- Sampling: Missing tool result or tool results mixed with other content