verify_image

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

With no annotations, the description carries the burden well: it discloses the fail-closed error policy, the per-check PASS/FAIL return shape, and the side effect of appending a receipt — that receipt append is important behavioral information an agent would otherwise miss. It stops short of stating auth requirements, whether verification is cached/expensive, or idempotency of repeated calls.

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

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

A single dense sentence covers scope, all checks, return shape, side effect, and failure mode, with the admission-control constraint front-loaded. No filler.

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

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

The return shape and side effect are described adequately despite there being no output schema, and no annotations exist to lean on. However, for a tool with a nested object parameter and zero schema documentation, the missing explanation of policy contents and policy/policy_id selection leaves a real gap before an agent can call it correctly.

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

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

Schema description coverage is 0% across three parameters, including a nested 'policy' object, so the description must compensate and largely does not. It never explains the 'image' format (tag vs digest), what the nested policy object must contain, or — most importantly — the precedence/relationship between 'policy' and 'policy_id'.

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

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

States a specific verb and resource ('Verify a container image') and enumerates the exact checks performed: registry allowlist, digest resolution, signature validity, signer identity, payload binding, and DSSE provenance. It is clearly distinct from the sibling tools policy_show and receipt_list, which read policy/receipt data rather than performing verification.

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

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

The phrase 'BEFORE it is allowed anywhere near a runtime' gives a clear gating/admission-control context for when to call it. It doesn't explicitly name when-not to use it or point at alternatives, but the siblings are obviously unrelated read tools, so the practical guidance is unambiguous.

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