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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered structurally. The description adds content-level context by enumerating what is returned (identity, grant, self-reported vs independently verified facts), but says nothing about auth requirements or response shape beyond that.

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 compact sentence that front-loads the primary content (agent identity). Nothing is wasted, though the trailing 'any independently verified facts' is slightly vague rather than informative.

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 must carry the return-value burden, and it does list the categories returned. It stops short of explaining the distinction between 'grant', 'self-reported profile', and 'independently verified facts', which an agent would benefit from knowing.

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% and the single optional agent_key parameter is fully documented in the schema, including its pba_ pattern and the omit-if-carried-in-header rule. The description adds nothing about parameters, so the baseline 3 applies.

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 names the specific resource returned (agent identity, grant, profile, verified facts), so an agent can tell what it fetches even though the verb is implicit in the name 'whoami'. It does not differentiate from the sibling 'my_account', which is a plausible source of confusion.

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?

There is no when-to-use guidance, no statement of prerequisites, and no routing to or away from 'my_account', 'enroll', or 'rotate_key'. The agent must infer that it calls this to learn its own identity.

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