error-handling-patterns

Rust MCP server error handling requires returning McpResult<T> from tool, resource, and prompt handlers while using McpError variants to map domain errors into JSON-RPC responses.

The MCP error architecture uses three layers: domain errors, framework conversions, and JSON-RPC responses. Handlers must return McpResult<T> to let the framework automatically convert McpError variants into proper protocol responses.

Selecting McpError variants for parameter validation involves using a decision tree that distinguishes parameter issues, execution failures, and not-found conditions to return the correct McpResult<T> from your handler.

Yes, you can convert domain errors to McpError using From implementations, map_err, and explicit constructors in tool, resource, and prompt contexts to satisfy the McpResult<T> return requirement.

Mapping tool execution failures to McpError variants relies on framework conversions and explicit constructors to translate domain errors into JSON-RPC errors while maintaining the McpResult<T> return type.

Generic JSON-RPC errors occur when handlers bypass the McpResult<T> return rule. You must use McpError constructors and conversion helpers to ensure the framework maps domain errors to the correct variants.