feat: operation input to MCP compatible json schema converter - #1124
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Co-authored-by: Ludwig <ludwig.bedacht@gmail.com>
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🤖 I have created a release *beep* *boop* --- ## [2.0.0-rc.170](v2.0.0-rc.169...v2.0.0-rc.170) (2025-04-17) ### Features * operation input to MCP compatible json schema converter ([#1124](#1124)) ([48cc99b](48cc99b)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).
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## Problem `BuildJsonSchema` inlines input types and truncates recursion at a fixed depth, dropping self-referential fields (e.g. `left`/`right`). With `additionalProperties: false`, valid nested payloads are then rejected: `additional properties 'left', 'right' not allowed`. The same input passes normal GraphQL; only the generated JSON Schema (MCP path) rejects it. Also fixes a tracker leak: the early `return nil` at the depth limit skipped cleanup, leaking the recursion counter across sibling uses of a type. ## Fix Emit `$ref`/`$defs` for recursive input types: a first pass finds self-/mutually-recursive types; each is emitted once under root `$defs` and referenced via `$ref`. Recursion terminates by construction and nesting works to any depth. Non-recursive types are unchanged (still inlined). `maxRecursionDepth` is kept on the exported signatures for compatibility but is now a no-op. ## Design note Revisits #1124, which deliberately dropped `$def` for LLM compatibility. That holds for non-recursive inputs (kept inline); for recursive inputs the only alternative to `$ref` is a schema that rejects valid data, so `$defs` is reintroduced for recursive types only. The validator (`santhosh-tekuri/jsonschema`) supports it. ## Tests - New `recursive_input_test.go`: validates a nested recursive payload against the generated schema using `santhosh-tekuri/jsonschema/v5`. - Updated the two tests that encoded the old truncation behaviour; non-recursive golden tests unchanged. Closes ENG-9631
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This pull request introduces a new
jsonschemapackage to handle JSON Schema definitions in thev2/pkg/engine/jsonschema/schema.gofile. The conversion logic was optimized for the use case to produce JSON schemas that are compatible with LLM (Large Language Models). This includes removing support for$defand working with a fixed recursion depth.The key changes include defining a
JsonSchemastruct, custom JSON serialization, and various helper functions to create and manipulate schema objects.Key changes:
JSON Schema Definition
JsonSchemastruct to represent a JSON Schema definition, including fields for core schema properties, array-specific fields, enum values, and additional validation.Custom Serialization
MarshalJSONmethod to theJsonSchemastruct to customize JSON serialization and omit empty fields.Helper Functions
NewObjectSchema,NewArraySchema,NewStringSchema,NewIntegerSchema,NewNumberSchema,NewBooleanSchema,NewEnumSchema).JsonSchemastruct to add descriptions, default values, formats, and nullable flags (WithDescription,WithDefault,WithFormat,WithNullable).Cloning Functionality
CloneSchemafunction to create deep copies of existing schema objects.