Agent JSON Reliability MCP server

Agent JSON Reliability

Deterministic JSON repair + JSON Schema validation for AI agents. No LLM. Safe refusal on ambiguity.

STATUS=BETA 0.1.0 · GitHub · PyPI · Official MCP Registry

Problem: agents emit malformed JSON (fences, trailing commas, single quotes). This tool inspects, safely repairs, and schema-validates that text. No LLM. No invented values.

Machine catalog: https://agent-json-reliability.onrender.com/v1/catalog Skill: https://agent-json-reliability.onrender.com/skill.md

Quick start

uvx agent-json-reliability

MCP client config (stdio, published package):

{
  "mcpServers": {
    "agent-json-reliability": {
      "command": "uvx",
      "args": ["agent-json-reliability"]
    }
  }
}

<!-- mcp-name: io.github.toninovo4249-ai/agent-json-reliability -->

AI agents and software frequently emit malformed JSON: markdown fences, trailing commas, single quotes, True/False/None, and extra prose around one object.

Agent JSON Reliability is a deterministic pipeline for that failure mode:

1. inspect — diagnose whether the text is JSON and which failures are present
2. safe repair — apply only structural, unambiguous fixes
3. validate — optional JSON Schema check on the result
4. structured diagnostics — validoriginal, repaired, validfinal, schemavalid, unsafeor_ambiguous, changes, errors

This is not a generic jsonschema wrapper. Missing semantic values are never invented. Ambiguous input is refused.

Primary HTTP endpoint (local/self-hosted): POST /v1/json/reliable

MCP tools (same core functions): reliablejson, validatejson, repairjson, inspectjson

Before / after (safe repair)

Malformed agent output:

{
  "text": "```json\n{\"name\":\"alice\",\"age\":30,}\n```"
}

Expected result (semantically equivalent valid JSON):

• valid_original=false
• repaired=true
• valid_final=true
• unsafeorambiguous=false
• json → {"name":"alice","age":30}

If a schema is supplied and satisfied: schema_valid=true.

Safe refusal (ambiguous)

Truncated input such as {"user": is JSON-intended but not deterministically repairable without inventing keys or values.

Expected:

• HTTP 200 (documented safe response)
• valid_final=false
• unsafeorambiguous=true or repaired=false

Do not treat a correct refusal as a product failure.

Run locally (no Hunter)

python -m pip install -r requirements.txt
python serve.py

Binds 127.0.0.1:8770 by default. Set PUBLICBASEURL to an HTTPS origin only when you expose the process yourself. Do not commit a temporary tunnel hostname as the canonical URL.

Hosted API (x402)

Public origin: https://agent-json-reliability.onrender.com

Inspect / validate / repair / MCP stay free. POST /v1/json/reliable returns HTTP 402 until an x402 PAYMENT-SIGNATURE settles 3000 atomic USDC (0.003) on Base (eip155:8453) via PayAI.

Shortened. The full README is on GitHub.