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Verify a server's polygraph attestation

verify_attestation
Read-onlyIdempotent

Read a server's published behavioral grade and attestation evidence to determine trustworthiness before agentic commerce.

Instructions

Read a server's already-published polygraph (litmus) grade — without running anything — before an agent trusts or, in agentic commerce, pays it.

When a grade is published it returns the behavioral grade (A–F), the attestation UID, the evidence CID, and the graded tool-surface fingerprint. The caller must still recompute the LIVE fingerprint and require it to equal the attested one before paying — a passing attestation can otherwise front for a tool surface the server no longer serves (rug pull).

Grade publishing is still rolling out, so this commonly returns not_available today: that means UNEVALUATED (neither safe nor unsafe), not a failing grade — to grade the server yourself right now, use run_litmus. A lookup_failed result means the lookup itself failed (the index or chain was unreachable); the grade is unknown, which is not the same as unevaluated.

Input: server_ref — e.g. npm/@modelcontextprotocol/server-filesystem.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
server_refYesRegistry-prefixed server identifier, e.g. npm/@scope/server.
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint and idempotentHint. The description adds valuable context: it explains the tool does not run anything, describes return fields (grade, UID, CID, fingerprint), discloses that grade publishing is rolling out so 'not_available' is common, and clarifies error semantics. No contradiction.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single well-structured paragraph. It front-loads the core purpose, then explains results, error handling, and ends with a parameter example. Every sentence adds value without fluff.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite no output schema, the description adequately explains return values (grade, UID, CID, fingerprint) and handles two special cases ('not_available' and 'lookup_failed'). Given the complexity of attestation verification, this is complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with a description for 'server_ref', but the description adds a concrete example and explains it's a registry-prefixed identifier, going beyond the schema's generic description.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool reads a published polygraph grade without running anything, specifying the verb 'read' and the resource 'server's polygraph attestation'. It distinguishes from sibling 'run_litmus' by stating when to use each.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit guidance: use before trusting/paying, use 'run_litmus' if grade is not published, and explains how to interpret results like 'not_available' vs 'lookup_failed'. Also warns about needing to recompute live fingerprint to prevent rug pull.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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