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

Annotations already declare readOnlyHint=true, openWorldHint=false, destructiveHint=false, so the safety profile is fully covered by structured data. The description adds the returned field set, which is genuine value, but says nothing about auth failure behavior, rate limits, or what happens with an invalid token.

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 useful payload (what is returned) and ending with the input requirement. Compact with minimal waste, though 'Input: token' is a slightly awkward tail that mostly repeats the schema.

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 a single optional parameter, full schema coverage, and annotations covering the read-only, non-destructive profile, the description supplies exactly the missing piece: the shape of the response. No output schema exists, so enumerating plan, limits, site count, and hostname count is the right call.

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% and the schema already explains the token format (deed_tok_...), the publish-time origin, and the optional fallback to the Authorization header. The description's lone 'Input: token' adds no new information beyond that, but with full schema coverage the baseline is 3 and there is no gap to compensate for.

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?

Specific verb (returns) plus enumerated resource details (plan, limits, site count, custom hostname count). It reads clearly as the account/token introspection tool and is distinguishable from siblings like list_sites or get_site, which operate on sites rather than the token's own plan/quota.

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 name whoami and the content of the response imply this is a diagnostic/token-info call, so usage is reasonably inferable. But there is no explicit guidance on when to reach for this versus revoke_token, rotate_token, or list_sites for inspecting account state.

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