# Keyronne JSON Schema Validator & LLM Output Coercer

> Keyronne JSON Schema Validator & LLM Output Coercer is a paid API for AI agents from keyronne.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-10).

Validates a JSON value against a JSON Schema and automatically coerces common LLM output mistakes (numbers as strings, stringified booleans, missing defaults, extra properties) before returning a corrected value and structured error report.

## Facts

- Endpoint: POST https://keyronne.com/api/validate-json?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/keyronne-json-schema-validator-llm-output-coercer-aa2e280e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_anzB0Q50hP8zWBUQvd5Gr

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability keyronne-json-schema-validator-llm-output-coercer-aa2e280e -d '<json body>'
```

Example prompt: My LLM returned {"name":"Ada","age":"36"} but the schema requires age to be an integer — can you validate it against the schema {"type":"object","required":["name","age"],"properties":{"name":{"type":"string"},"age":{"type":"integer"}}} and coerce any type mismatches so I get back a clean, corrected value?

## When to prefer this

Use this endpoint whenever an LLM or AI agent returns structured output (tool-call arguments, function parameters, or JSON responses) that needs to be validated and lightly repaired before downstream use. Ideal when the LLM frequently makes type coercion mistakes like returning numbers as strings or booleans as 'true'/'false' strings. Prefer this over a generic JSON validator when you also need auto-coercion and default-filling, not just a pass/fail result.

## Known failure modes

- Schema itself is invalid — returns error describing the schema parsing failure
- Data cannot be coerced to the required type (e.g. a non-numeric string where an integer is required) — reported in the error section with the offending field path
- Missing required fields that have no default and cannot be inferred — flagged in the error report
- Malformed request body (missing schema or data fields) — returns 400-level error
- Unsupported JSON Schema keywords outside the supported draft-07 subset — may be silently ignored or flagged

## How this service works

Validate a JSON value against a JSON Schema and coerce common LLM-output mistakes (numbers as strings, stringified booleans, scalars where arrays are expected, missing defaults, extra properties). Returns the coerced value plus a structured error report. Built for cleaning up LLM tool-call arguments and structured outputs. POST a JSON body like: {"schema":{"type":"object","required":["name","age"],"properties":{"name":{"type":"string"},"age":{"type":"integer"}}},"data":{"name":"Ada","age":"36"}}

## Output

Returns the coerced/corrected JSON value (with type fixes applied, defaults filled, extra properties stripped) plus a structured error report listing any fields that could not be coerced, constraint violations, and a summary of what was changed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "data": {
   "description": "The candidate JSON value to validate and coerce."
  },
  "coerce": {
   "type": "boolean",
   "default": true,
   "description": "Attempt type coercion and default-filling before validating."
  },
  "schema": {
   "type": "object",
   "description": "JSON Schema (draft-07 style subset: type, properties, required, items, enum, const, additionalProperties, min/max constraints, pattern, default)."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/keyronne-json-schema-validator-llm-output-coercer-aa2e280e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from keyronne.com](https://www.zero.xyz/host/keyronne.com/llms.txt)