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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavior: the three possible outcomes (valid, expired, not found) and the privacy constraint that the holder's name is never returned, which prevents the agent from planning to surface or request a name. It does not address malformed certificate numbers or rate limits, keeping it short of a 5.

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?

Two sentences, front-loaded with the core action and followed by the return contract. Every clause carries information: issuer, legal basis, required inputs, possible outcomes, and the privacy constraint; nothing is repeated.

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?

With no output schema, the description carries the burden of explaining returns and does so explicitly (valid/expired/not found plus issue and expiry dates). Combined with fully documented parameters and rich annotations on a simple two-parameter read tool, nothing an agent needs to call it correctly is missing.

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 100%, so the schema already explains both parameters, including the example format '1-000301'. The description's phrase 'using the certificate number and the holder's surname' merely restates the two inputs and adds no format or matching rules beyond the schema — baseline 3.

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: 'Check whether a SafeHandle manual handling certificate ... is valid'. It further scopes the tool by naming the issuer (A1RO) and legal basis (S.I. No. 299 of 2007), so the agent knows exactly what is being verified and against which credential scheme.

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 makes the lookup context clear by stating the two pieces of evidence needed ('certificate number and the holder's surname'), which implies the verification use case. It does not name any alternative tool or state when not to use this one, but the sibling tools are unrelated, so the practical gap is small.

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