JSON Schema Validation Skill

Overview

JSON Schema Validator works by comparing JSON data against a JSON Schema definition. It validates types, required fields, string patterns, numeric ranges, array constraints, and format specifications.

Live Test JSON Schema Validation Skill Skill →

The tool

Once your client is connected to the VerveKit server, this appears in its tool list as JSONSchemaValidationSkill. It is read-only and open-world — it fetches and never mutates anything on your side — so most clients call it without asking you to confirm.

Tool call

{
  "name": "JSONSchemaValidationSkill",
  "arguments": {
    "schema": "{\"type\":\"object\",\"properties\":{\"name\":{\"type\":\"string\"}},\"required\":[\"name\"]}",
    "json": "{\"name\":\"John\",\"age\":30}"
  }
}

You do not name the tool yourself; the model picks it. Asking about {"type":"object","properties":{"name":{"type":"string"}},"required":["name"]} in the terms this skill covers is enough for it to reach for JSONSchemaValidationSkill on its own — naming it explicitly also works, and is the way to force the call.

Connecting

One server URL covers every skill in the catalog, including this one. Authorization is OAuth: the client opens a browser once, and there is no key to paste into a config file.

{
  "mcpServers": {
    "vervekit": {
      "url": "https://api.vervekit.com/v1/mcp"
    }
  }
}

Per-client setup — Claude, Cursor, VS Code, ChatGPT — is on the MCP setup page.

Arguments

These are the properties on the tool's inputSchema, so a well-behaved client validates them before the call is made. Premium arguments are accepted on every plan but only take effect on plans that include them.

Argument	Type	Description
`schema`Required	object	The JSON Schema to validate against
`json`Required	object	The JSON data to validate. An empty object is a valid document and is accepted.

What the model gets back

The result carries a structuredContent object matching the tool's declared outputSchema, so a client reads fields without parsing prose. status is "ok" and error is null on success; a null field means the value was not available for that input, not that the call failed.

Result

{
  "status": "ok",
  "error": null,
  "data": {
    "valid": true,
    "errors": [],
    "error_count": 0
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Field	Type	Example	Description
`valid`	boolean	`true`	Whether the JSON data is valid against the schema
`errors`Premium	array	`[]`	Array of validation error messages
`error_count`	number	`0`	Number of validation errors found

Failure modes

Errors come back as tool errors carrying a sentence the model can act on, not a bare status code. Error handling covers the full list.

Status	What it means
`400` / `422`	The arguments did not validate. The message names the offending one.
`401`	The OAuth session is invalid or expired — reconnect the server.
`403`	Blocked by a key restriction or an IP allow-list. Never a bad identity.
`404`	This skill is not part of VerveKit. Check the catalog.
`429`	Out of credits, or a brief rate limit. The message tells them apart.

A call costs 2 credits each time the tool actually runs; a model that reasons about the tool without calling it costs nothing.

Use cases

API Validation: Validate incoming API request payloads against defined schemas before processing to ensure data quality
Configuration Files: Verify configuration files match expected schemas before deployment to prevent runtime errors
Data Quality: Validate data integrity in ETL pipelines by checking against schemas during data transformation
Contract Testing: Ensure API responses match contract specifications by validating against JSON schemas in tests

Other ways to use JSON Schema Validation Skill

Set up JSON Schema Validation Skill on VerveKit, or reach the same source a different way. Your VerveKit account and credits work on all of them — one key, one balance.

Call it as a REST APIOne HTTPS endpoint and an x-api-key header, with SDKs for Node, Python and .NET.APIVerve →Reference →