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

Beyond the readOnlyHint annotation, the description discloses the online trust model, the fact that the server fetches the signing-key registry, the convenience-vs-trust tradeoff, and the free/no-payment nature. It also exposes the operational difference between lookup-based and direct-envelope verification, which is genuinely useful behavioral context.

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?

The description is front-loaded with the core outcome and then covers input modes and trust caveats without excessive fluff. Each sentence adds information, including the offline alternative, though the trust-model explanation is somewhat longer than strictly necessary.

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?

For a simple read-only, two-parameter tool with no output schema, the description covers invocation modes, input constraints, result categories, and the key trust caveat. Nothing critical is missing for an agent to decide whether and how to call this tool 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 coverage is 100%, so the baseline is already 3, but the description adds meaningful semantics: receipt_id triggers a lookup with a public-required condition, while envelope is verified directly without requiring publication. It reinforces mutual exclusivity and clarifies the envelope's shape ({schema, receipt, proof}), going beyond the bare schema descriptions.

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?

The description states a specific verb ('checks'), a specific resource ('receipt'), and names the three possible outcomes ('VALID, INVALID, or UNVERIFIABLE') with a reason code. This clearly distinguishes it from sibling verification tools like verify_uk_company and verify_us_company, which target different entities.

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 description gives concrete usage guidance: use receipt_id for a public lookup or pass an existing envelope for direct verification, and notes the public requirement and that no publication is needed. It also mentions the offline package as a stronger trust alternative, though it does not explicitly name sibling tools like get_receipt as alternatives or state exact conditions for when to prefer them.

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