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

Annotations already cover read-only, idempotent, non-destructive and non-open-world, but the description adds real context beyond them: the need for openid/email consent, the guarantee that the ID is stable across token refresh, reconnection and display-name/email changes, and an explicit scope caveat that the read grants no project or business permissions.

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?

Three sentences, front-loaded with the core behavior and each carrying distinct payload (what it returns, why the ID matters, what it needs and does not grant). No repetition of the title or filler.

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, return values need no explanation. For a zero-parameter read, the annotations plus the description's auth prerequisite and permission-scope caveat cover everything an agent needs to invoke it correctly.

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, which is the baseline-4 case; there is nothing for the description to disambiguate. Schema coverage is 100% and additionalProperties is false, so no parameter gap exists.

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 gives a specific verb and resource: it returns the profile bound to this request's validated credentials, i.e. the identity of the connected account. It is clearly distinguishable from every sibling, which all operate on domain data (projects, campaigns, cap tables) rather than account identity.

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 establishes the context of use ('the profile represented by this request's validated credentials') and a prerequisite ('requires openid and email consent'), which tells an agent when it is callable. It does not name explicit when-not conditions or alternatives, but no competing identity sibling exists.

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