Verify a skill's polygraph attestation
verify_skill_attestationVerify a skill's published safety grade (A/B/D/F) from Polygraph before installation. Returns attestation UID, evidence CID, and content hash for integrity check.
Instructions
Read a Claude Code / Agent Skill's already-published polygraph grade — without running anything — before an agent installs or trusts it.
When a grade is published it returns the letter (A/B/D/F), the attestation UID, the evidence CID, and the attested contentHash. The caller MUST then recompute the skill's content hash (sha256 over every file the SKILL.md can load, including lazily-referenced files) and require it to equal contentHash before installing — a passing attestation can otherwise front for different bytes (a swapped bundled script). The ref/version is advisory; the contentHash is the trust anchor.
Grade publishing for skills is rolling out, so this commonly returns not_available:
that means UNEVALUATED (neither safe nor unsafe), not a failing grade — to grade a
local skill yourself, use run_skill_litmus. A lookup_failed result means the
lookup itself failed (index/chain unreachable); the grade is unknown, not unevaluated.
Input: skill_ref — e.g. github//# or marketplace//.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| skill_ref | Yes | Skill identifier, e.g. github/<owner>/<repo>#<path> or marketplace/<owner>/<name>. |