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

The annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description then adds genuinely non-obvious context beyond the annotations: the returned id is opaque, app-scoped, and stable across token refresh, reconnection, and display-metadata changes — exactly what an agent needs to know before caching or comparing ids. It does not, however, say anything about auth failure behavior or scope requirements.

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, both front-loaded with the essential claim: first what is returned, then why the returned id is trustworthy. There is no filler and nothing is buried.

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 an output schema present and rich annotations, the description doesn't need to explain return fields, and the stability note covers the main operational gotcha. A brief statement of when to call it (e.g., to verify identity after a token refresh) would close the remaining gap.

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 takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a no-parameter tool is a 4. The description correctly implies the credential context is derived from the request itself rather than passed as an argument.

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 a specific verb ('Return') and a specific resource ('the profile represented by this request's authenticated credentials'), which makes clear this is a self-scoped identity lookup rather than an arbitrary user lookup. It stops short of distinguishing this from siblings explicitly, but no sibling tool in the list covers the same operation, so ambiguity is low.

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 phrase 'this request's authenticated credentials' implies the use case (identify the caller of the current session), but the description never states when to reach for this tool, nor does it flag any exclusions or follow-up tools. Usage is inferable rather than instructed.

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