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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety profile is covered. The description adds genuinely new behavior: identity comes from credentials rather than arguments, and the returned opaque ID is stable across refresh and reconnection — important for caching or re-keying decisions. No return shape detail is given, but an output schema exists, so that is acceptable.

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 short sentences with zero filler: what it returns first, the identity stability second, the usage constraint last. Every sentence carries distinct information and the most decision-relevant clause is front-loaded.

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?

For a no-argument read tool with a rich annotation set and an output schema, the description covers identity source, ID stability, and the no-selector rule. The only unstated item is behavior on invalid or expired credentials, a minor gap given the annotations and schema already carry the rest.

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?

Zero parameters, so the baseline is 4. The description reinforces the empty schema by warning that no account selector exists, preventing an agent from inventing one, but it adds nothing else parameter-related because there is nothing to describe.

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?

States a specific verb and resource ("Returns the single profile") and immediately scopes it to the account bound to the validated credentials. The clause "never supply an account selector" separates it from the project-scoped siblings (dub_get_project, dub_list_projects) without needing their schemas.

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?

Gives an explicit use case ("Use to identify the connected account") plus a hard exclusion ("never supply an account selector"), which is exactly the guidance an agent needs for a zero-parameter tool. It stops short of naming an alternative tool for per-project identity lookups, so it is clear context rather than full when/when-not routing.

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