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

Beyond the annotations (which only flag openWorld, non-destructive, idempotent non-read), the description discloses two behavioral facts an agent cannot infer: no account is created, and the name reservation expires after fifteen minutes. The 15-minute TTL and the exclusivity guarantee ('so nobody else takes it') are exactly the kind of context annotations cannot carry.

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 action (get a link), then the human hand-off, then the scope limits. No filler, and every sentence carries distinct information.

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 only one fully documented parameter, an output schema that covers the return value, and annotations covering safety, the description supplies everything else an agent needs: the human-in-the-loop workflow, the reserved-name lifetime, and the fact that no account exists afterward.

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 already documents the single 'username' parameter with an example, so the baseline is 3. The description adds real meaning on top: the value is prefilled into a link and held for fifteen minutes, implying a uniqueness/reservation conflict if the name is taken, which clarifies what the parameter actually does.

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: 'Get a link that opens Kulhad sign-up with a page name already filled in.' The scope ('does not create an account') separates it conceptually from account-creating flows, but no sibling (e.g. check_username_available) is named, so the differentiation is implicit rather than explicit.

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 clearly states how the tool is meant to be used: 'Hand the link to the person setting up the page: they finish it themselves in a browser.' That is a clear context with an implied exclusion (this is not an automated account-creation step), though it never contrasts with the closest sibling, check_username_available.

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