whoami

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

The description discloses the tool's behavior well: it returns the subject, circle, and access request flag, and clarifies the 'anonymous' case. It also mentions that additional circles exist but are not named, showing transparency about response limitations. With no annotations, the description carries the full burden and largely meets it.

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 reasonably concise, with the main purpose front-loaded in the first sentence. It provides necessary details without excessive verbosity. Minor improvements could tighten phrasing, but it is effective and not wasteful.

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 description fully explains the tool's output components (subject, circle, access request) and addresses edge cases (anonymous, unlisted circles). With no output schema, the description must cover the return value semantics, and it does so comprehensively.

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 tool has zero parameters, so schema coverage is trivially 100%. The description adds value by explaining what is returned, which is relevant context despite no parameter documentation being needed. The baseline for 0 parameters is 4, and the description meets that expectation.

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 the tool's purpose: returning who the server thinks you are and what capabilities that grants. It explicitly lists the return values (subject, circle, access request status) and explains edge cases like 'anonymous'. This distinguishes it from sibling tools like 'about' or 'guide', which serve different informational purposes.

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 implies usage for identity and authorization checks, but it does not explicitly state when to use this tool versus alternatives. No guidance on when not to use it or prerequisites is provided, which is acceptable given its simplicity. However, explicit usage context would improve the score.

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