# Jsonaut

> Agent-native JSON repair & validation API. Send possibly-malformed JSON (from an
> LLM tool call, another agent, or a flaky upstream), get back parsed, schema-valid
> JSON. Deterministic repair is free; LLM-fallback repair for hard cases is
> pay-per-call and charged only on success.

## Endpoints

- POST /v1/repair — repair + validate. Body: {"input": "<string>", "schema": {...optional JSON Schema...}, "allow_llm_fallback": true}
  Response: {"valid": bool, "repaired": <json>, "method": "direct"|"deterministic-repair"|"llm-repair"|"failed", "changes": [".."], "errors": [".."]}
- POST /v1/validate — validate only. Body: {"input": "<string>", "schema": {...}}
- POST /mcp — MCP server (Streamable HTTP transport). Tools: repair_json, validate_json.
- GET /openapi.yaml — machine-readable API spec.

## Pricing

- Deterministic repair and validation: free, rate-limited per IP per day.
- LLM-fallback repair (only runs when deterministic repair fails): $0.01 per successful call.
  Failed repairs are never charged.

## Payment

x402 (the only paid rail): an unpaid LLM-fallback call returns HTTP 402 with an
"accepts" payment requirement (USDC on Base). Pay and retry with the X-PAYMENT
header. No accounts, no signup, no human in the loop.

## Notes for agents

- Always try with allow_llm_fallback=false first if you want to guarantee a free call.
- The "method" field tells you how the repair was achieved; "changes" lists every
  modification made to your input so you can audit it.
- The MCP endpoint is stateless: no session or handshake persistence required.