* fix: address PR review - schema_for_output no longer validates or returns Result
- Add strip_output() that strips title/description without validating type (Dale #1)
- Change schema_for_output to return Arc<JsonObject> instead of Result (Dale #2)
- Cache only Arc<JsonObject> success values, not Result (Dale #3)
- Remove dead unwrap_or_else panic paths in with_output_schema, ToolBase, and macros
- Tighten test assertions from contains to assert_eq on type field (Dale #4)
- Update test_schema_for_output_rejects_primitive to accept_primitive (SEP-2106)
Co-authored-by: Orca <help@stably.ai>
* test(rmcp): add non-object output schema tests for SEP-2106
Add tests verifying schema_for_output accepts non-object types:
- test_tool_builder_methods: primitive (i32), array (Vec<String>), option
- test_structured_output: tool returning Json<Vec<T>> and Json<i32>
- test_json_schema_detection: Json<Vec<T>>, Result<Json<Vec<T>>,E>, Json<String>
- tool_traits: ToolBase::output_schema with Vec<AddOutput> output type
* test(rmcp): add missing edge case tests from code review
Add tests identified during code review:
- description stripping for primitive types
- composition types (Option<String> with anyOf/oneOf/null)
- cache correctness (Arc::ptr_eq for repeated calls)
- schema_for_input rejecting array types (not just primitives)
- schema_for_output accepting unit type ()
* feat!: mark schema_for_output return-type change as breaking
This introduces SEP-2106: schema_for_output no longer validates or
returns Result. The public signature changed, so bump major.
* fix: address Dale's PR review - direct schema.get assertions, remove ArrayTool
- Replace loose schema_str.contains(...) assertions with direct
schema.get("type") equality checks in test_tool_builder_methods.rs
and test_structured_output.rs
- Remove redundant ArrayTool fixture and its round-trip
serde_json::from_str test from tool_traits.rs since schema is
already Arc<JsonObject>
- Drop dead schema_str variable in test_structured_output.rs
---------
Co-authored-by: Brandon Bennett <brandonbennett@macbookair.myfiosgateway.com>
Co-authored-by: Orca <help@stably.ai>
Co-authored-by: Brandon Bennett <brandonbennett@Pursuits-Air.lan>
* feat: add output_schema field to Tool struct
- Add optional output_schema field to Tool struct for defining tool
output structure
- Update Tool::new() to initialize output_schema as None
* feat: add structured_content field to CallToolResult
- Add optional structured_content field for JSON object results
- Make content field optional to support either structured or
unstructured results
- Add CallToolResult::structured() and structured_error() constructor
methods
* feat: implement validation for mutually exclusive content/structuredContent
- Add validate() method to ensure content and structured_content are
mutually exclusive
- Implement custom Deserialize to enforce validation during
deserialization
- Update documentation to clarify the mutual exclusivity requirement
* feat: add output_schema support to #[tool] macro
- Add output_schema field to ToolAttribute and ResolvedToolAttribute
structs
- Implement automatic output schema generation from return types
- Support explicit output_schema attribute for manual specification
- Generate schemas for Result<T, E> where T is not CallToolResult
- Update tool generation to include output_schema in Tool struct
* feat: implement IntoCallToolResult for structured content
- Add Structured<T> wrapper type for explicit structured content
- Implement IntoCallToolResult for Structured<T> with JSON serialization
- Add support for Result<Structured<T>, E> conversions
- Enable tools to return structured content through the trait system
* fix: update simple-chat-client example for optional content field
- Handle Option<Vec<Content>> in CallToolResult.content
- Add proper unwrapping for the optional content field
- Fix compilation error in chat.rs
* fix: update examples and tests for optional content field
- Add output_schema field to Tool initialization in sampling_stdio
example
- Update test_tool_macros tests to handle Option<Vec<Content>>
- Use as_ref() before calling first() on optional content field
* feat: implement basic schema validation in conversion logic
- Add validate_against_schema function for basic type validation
- Add note that full JSON Schema validation requires dedicated library
- Document that actual validation should happen in tool handler
* feat: add structured output support for tools
- Add output_schema field to Tool struct for defining output JSON schemas
- Add structured_content field to CallToolResult (mutually exclusive with content)
- Implement Structured<T> wrapper for type-safe structured outputs
- Update #[tool] macro to automatically generate output schemas from return types
- Add validation of structured outputs against their schemas
- Update all examples and tests for breaking change (CallToolResult.content now Option)
- Add comprehensive documentation and rustdoc
- Add structured_output example demonstrating the feature
BREAKING CHANGE: CallToolResult.content is now Option<Vec<Content>> instead of Vec<Content>
Closes#312
* fix: correct structured output doctest to use Parameters wrapper
The #[tool] macro requires Parameters<T> wrapper for tool inputs.
This fixes the pre-existing broken doctest in the structured output
documentation example.
* feat: replace Structured<T> with Json<T> for structured output
- Remove Structured<T> type definition and implementations
- Reuse existing Json<T> wrapper for structured content
- Update IntoCallToolResult implementations to use Json<T>
- Add JsonSchema implementation for Json<T> delegating to T
- Update all examples and tests to use Json<T> instead of Structured<T>
- Update documentation and exports
BREAKING CHANGE: Structured<T> has been replaced with Json<T>. Users must update their code to use Json<T> for structured tool outputs.
* feat: add output_schema() method to IntoCallToolResult trait
- Add output_schema() method with default None implementation
- Implement output_schema() for Json<T> to return cached schema
- Implement output_schema() for Result<Json<T>, E> delegating to Json<T>
- Enable trait-based schema generation for structured outputs
* feat: update macro to detect Json<T> wrapper for output schemas
- Add extract_json_inner_type() helper to detect Json<T> types
- Update schema generation to only occur for Json<T> wrapped types
- Remove generic Result<T, E> detection in favor of specific Json<T> detection
- Add comprehensive tests to verify schema generation behavior
* feat: add builder methods to Tool struct for setting schemas
- Add with_output_schema<T>() method to set output schema from type
- Add with_input_schema<T>() method to set input schema from type
- Both methods use cached_schema_for_type internally
- Add comprehensive tests for builder methods
* fix: address clippy warnings
- Add Default implementation for StructuredOutputServer
- Fix collapsible else-if in simple-chat-client
- No functional changes
* style: apply cargo fmt
Apply automatic formatting changes to:
- examples/simple-chat-client/src/chat.rs - fix line wrapping
- crates/rmcp-macros/src/tool.rs - format method chaining
- examples/servers/src/structured_output.rs - reorder imports and format function signatures
* chore: fix formatting
* chore: fix rustdoc redundant link warning
* refactor: validate_against_schema
* feat: enforce structured_content usage when output_schema is defined
This commit implements strict validation to ensure tools with output_schema
consistently use structured_content for both success and error responses.
Changes:
- Enhanced ToolRouter::call() validation to require structured_content when output_schema is present
- Added validation that tools with output_schema cannot use regular content field
- Added comprehensive tests covering the new strict validation behavior
- Created example demonstrating proper structured output usage
- Updated TODO.md to track validation improvements
This ensures consistent response format and better type safety for MCP clients.
* chore: remove TODO.md
* refactor: simplify output schema extraction logic in tool macro
- Extract complex nested logic into dedicated helper function
- Replace deeply nested if-else chains with functional approach
- Use early returns and ? operator for cleaner code flow
- Reduce 46 lines to 7 lines in main logic while improving readability
* chore: run cargo fmt
* fix: enforce structured_content usage when output_schema is defined
Structured content is returned as a JSON object in the structuredContent
field of a result.For backwards compatibility, a tool that returns
structured content SHOULD also return the serialized JSON in a
TextContent block.
https://modelcontextprotocol.io/specification/2025-06-18/server/tools#structured-content
Tools may also provide an output schema for validation of structured
results. If an output schema is provided:
- Servers MUST provide structured results that conform to this schema.
- Clients SHOULD validate structured results against this schema.
https://modelcontextprotocol.io/specification/2025-06-18/server/tools#output-schema
* chore: cargo fmt
Brandon Bennett