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Screwtape.ai — Judge Agent as a Service
x402
Screwtape.ai — Judge Agent as a Service is a paid API for AI agents from screwtape.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-30).
Evaluates agent output against a task and criteria, returning a pass/fail/retry verdict with a confidence score and reasons.
Price / call$0.005
Success—
StatusUnknown
How this service works
API for pass, fail, or retry verdicts on agent output, plus multi-agent consensus and false-consensus risk.
Output
Returns a JSON object containing a verdict enum (pass, fail, or retry), a numeric confidence score (0–1), an array of human-readable reasons explaining the verdict, a request_id for tracking, optional retention metadata if retain was set, and the engine type used (e.g. deterministic or model-based).
Example use cases
Automated QA gate for a research agent
“My research agent just produced this output: 'The Treaty of Versailles was signed in 1920 and ended World War I.' The task was 'Describe the Treaty of Versailles' and my criteria are ['correct year of signing', 'correct war it ended']. Use this evidence: 'The treaty was signed June 28, 1919' — can you judge whether this passes, fails, or needs a retry?”
Content accuracy check for a writing agent
“I need you to evaluate my writing agent's output against the task 'Write a product description for our new wireless headphones' with criteria ['mentions noise cancellation', 'mentions battery life', 'no false claims'] and this evidence from our spec sheet: 'ANC enabled, 40hr battery'. The agent output was: 'Experience crystal-clear sound with active noise cancellation and a 30-hour battery.' Give me a verdict and score.”
Regression testing for a customer support bot
“Can you judge this support bot response for the task 'Answer: how do I reset my password?' with criteria ['mentions email link', 'steps are under 3 sentences', 'does not mention phone support'] and the agent output 'Click the reset link sent to your email, then follow the instructions to set a new password'? Tell me if it passes, fails, or should retry.”
Technical details
Endpoint
POSThttps://screwtape.ai/v1/judge?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a structured, auditable pass/fail/retry verdict on LLM or agent output — especially when you have explicit criteria and supporting evidence to ground the evaluation. It is ideal for automated QA pipelines, agent self-evaluation loops, and regression testing where you need scored, reasoned verdicts rather than a raw similarity score or human review. Prefer it over prompt-based self-critique when you want deterministic, evidence-grounded checks with a machine-readable verdict enum.
Side effects
- Missing required fields (task, agent_output, or criteria) result in a 400 error
- Evidence array not grounded in the output may cause inaccurate heuristic scoring
- Very long agent_output or criteria arrays may exceed token/processing limits
- If criteria are ambiguous or contradictory, the verdict may be unreliable
- Payment failure (x402) blocks the call entirely with a 402 response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| task | string | |
| retain | boolean | |
| version | string | Optional version tag for that agent. |
| agent_id | string | Optional tag for the agent making this call. |
| criteria | array | |
| evidence | array | |
| agent_output | string |
Output
Schema · Response
{
"type": "json",
"schema": {
"type": "object",
"required": [
"verdict",
"score",
"reasons",
"request_id"
],
"properties": {
"score": {
"type": "number"
},
"engine": {
"type": "string"
},
"reasons": {
"type": "array",
"items": {
"type": "string"
}
},
"verdict": {
"enum": [
"pass",
"fail",
"retry"
],
"type": "string"
},
"retention": {
"type": "object"
},
"request_id": {
"type": "string"
}
}
},
"example": {
"score": 0.9,
"checks": [],
"claims": [
{
"text": "The crew size was 4.",
"status": "supported"
},
{
"text": "The mission launched from Cape Canaveral.",
"status": "supported"
}
],
"engine": "deterministic",
"reasons": [
"2 of 2 claims are grounded in the supplied evidence.",
"2 of 2 criteria matched the output.",
"Deterministic string checks only. No model was called."
],
"verdict": "pass",
"retention": {
"retained": false
},
"request_id": "example-request-id",
"verification": "heuristic"
}
}Tags
x402
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