component-shape-mcp

component-shape-mcp provides typed JSON Schema, strict argument decoding, shared tool registries, structured results, composed servers, and stdio support for Rust applications that expose component contracts through MCP. It is the protocol-facing crate in the component-shape project. Koruma is the ecosystem's canonical domain validator; applications choose its rules and own authorization and handler policy.

Overview

• Derive McpToolInput for named tool arguments with strict field decoding.
• Use McpJsonSchema for nested schemas and McpToolValue for values that pair a schema with a decoder.
• Follow Serde's deserialization names or choose explicit MCP wire-name overrides.
• Reject duplicate field spellings and unknown arguments with strict tool-input decoding.
• Register typed handlers in McpToolRegistry and return structured results.
• Use add_koruma_tool or add_koruma_tool_async to execute Koruma rules on decoded inputs before their handlers run. Server builders expose koruma_tool and koruma_tool_async for the same contract.
• Validate successful output against compiled JSON Schemas, with bundled references and no external retrieval. Formats remain annotations; output uses the exact advertised names.
• Install a reusable registry with McpServer::from_tool_registry, or compose tools, resources, and prompts directly in McpServer.

Validate domain input

Derive McpToolInput and koruma::Koruma on arguments with domain rules, then register through add_koruma_tool. It requires Koruma's ValidateExt and ValidationIssues contracts. The runtime integration uses koruma-core; add the koruma facade and koruma-collection in applications that derive or use built-in validators.

Validation failures return structured form, field, or element issues, preserving the validator, source field, label, index, and runtime parameters. Parameter values keep their JSON types. Opaque values use { "kind": "opaque", "type_name": ... }; non-finite floats use { "kind": "f64", "value": ... }. A custom error with no issues still fails with a form-level issue. Use McpValidationIssue::from(&issue) or koruma_validation_error(&error) when an integration needs shared conversion, and validate_koruma(&input) after constructing an untyped tool's domain value.

Schemas and strict decoding enforce protocol structure. Koruma executes domain rules; schema hints describe constraints to clients. Successful results retain the output-schema checks described above.