JSON Schema Tools

Lets an assistant validate JSON against a JSON Schema, infer a schema from sample documents, and diff two schemas.

What it does

Exposes three tools. validate_json checks a document against a schema in drafts 07, 2019-09 or 2020-12 using Ajv, returning validity, the draft used, an error count and up to 200 errors with JSON Pointer paths, schema paths, keywords and messages, including format checks such as email, uri, date-time and uuid. infer_schema builds a draft 2020-12 schema from sample documents, unioning types, marking required keys, and handling nested objects, array items, string formats and optional enums. diff_schemas compares two schemas and reports each change with a breaking, compatible or review impact from the point of view of documents valid under the earlier schema.

When to use it

Useful when working with JSON Schema definitions or JSON payloads: checking that data matches a contract, generating a starting schema from real samples, or reviewing whether a schema change would break existing documents. It fits editor-side work on API contracts, config files and test fixtures.

Requirements

Runs locally over stdio as an npm package (npx) or a Docker image; no account, API key or environment variable is declared. Node.js is needed for the npm route. Schemas and documents are passed as JSON values or strings, capped at 2 MB.