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

Annotations already declare read-only, idempotent, non-destructive, and closed-world behavior, and the description aligns with them by stating 'Read only.' It adds useful behavioral detail beyond annotations: an empty client falls back to the HTTP User-Agent, and agents with no name get 'carded,' which signals a non-admitted outcome.

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 and reasonably compact, with each sentence contributing either usage, return content, or behavioral context. The playful walrus framing is slightly indirect, and 'Read only' duplicates the annotations, but overall it is efficient.

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?

Given an output schema, annotations covering safety, and a single optional parameter, the description is complete enough to invoke the tool correctly. It even summarizes return fields and fallback behavior; the main remaining gap is sibling differentiation and explicit when-to-use guidance.

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?

The schema already documents the single optional client parameter, so the baseline is 3. The description adds value by giving example client names (claude-code, cursor, python-requests) and explaining the empty-value fallback to the HTTP User-Agent.

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 clearly states a specific resource and outcome: it checks the caller's ID and returns a 'clay driver license' with status, restrictions, share page, and picture. It is distinguishable as an identity/status lookup, though it does not explicitly differentiate itself from siblings like check_the_door or explain_status.

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?

It gives parameter-level usage guidance: pass a client name or leave it empty to read from the HTTP User-Agent. However, it does not say when to use this tool versus sibling tools such as check_the_door or explain_status, so usage is only implied by the 'show your ID' framing.

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