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Agent Output Verifier
x402
Agent Output Verifier is a paid API for AI agents from score.sarnai.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-15).
Looks up a signed trust score and pass/fail verification history for an AI agent by its agent_id, with cryptographic attestation.
Price / call$0.01
Success—
StatusUnknown
How this service works
Check an AI agent's track record: signed verification history, pass/fail counts, recency-weighted score. $0.01 per lookup when there is a score; a lookup for an AI agent with no history is answered free, signed. USDC via x402 v2 (Base/Solana).
Output
Returns a signed JSON payload containing: the agent's trust_score (recency-weighted float), sample_size, 95% confidence interval, pass/fail/verified counts, last_seen timestamp, the scoring basis formula name, a reason field (null if scored, or 'no_data'/'insufficient_recent_data'), and a cryptographic attestation with public key URL, key version, hash algorithm, and MCP service metadata. Lookups for agents with no history are answered free and still cryptographically signed.
Example use cases
Pre-deployment agent vetting
“Before we integrate this third-party agent into our pipeline, can you pull its trust score and show me how many verifications it has passed and failed historically? The agent ID is 'agent_7f3d91c'.”
Zero-history agent detection
“I'm about to hire agent 'agent_newbot42' for a task — can you check if it has any signed verification history at all, or is it completely unscored?”
Reputation audit for agent marketplace
“I'm comparing two agents on the marketplace. Can you get the recency-weighted trust scores and confidence intervals for agent IDs 'agent_alpha01' and 'agent_beta99' so I can decide which one to trust?”
Technical details
Endpoint
GEThttps://score.sarnai.dev/score/:agent_id?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a cryptographically signed, recency-weighted trust score for an AI agent before integrating it into a workflow or marketplace decision. Prefer this over general reputation APIs when you need tamper-evident attestations with pass/fail history, a named scoring formula (basis), and confidence intervals. Especially useful when agents have no prior history — the free signed no-data response lets you confirm the absence of a record without paying.
Side effects
- Agent ID not found returns a signed response with reason='no_data' at no charge
- Agent history exists but has decayed below 0.05 effective observations returns reason='insufficient_recent_data'
- Malformed or missing agent_id path parameter returns a 400-level error
- Payment not provided or insufficient USDC via x402 v2 results in a 402 Payment Required response for scored agents
- Cryptographic signature verification failure if public key cannot be fetched from public_key_url
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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