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

With no annotations, the description carries the full burden and does it well: it discloses the return value (verification_url), the side effect model (it does NOT accept emails and does NOT send email), the human-in-the-loop requirement (user must open the URL and confirm), and anti-patterns the agent must avoid (no fabricated emails, no request loops). This is far more than a restatement of the name.

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?

Front-loaded with the action and the key constraint, then flows into the human-confirmation workflow and polling rules. Every sentence carries a distinct instruction or constraint; nothing is padding.

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?

No output schema and no annotations exist, yet the description supplies the return handle (verification_url, request_id), the follow-up tool, the polling interval convention, and expiry handling. Nothing essential for correct invocation is missing.

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 and the schema is empty at 100% coverage, so the baseline is 4. The description correctly implies no input is needed and instead points at the output (request_id, verification_url) that drives subsequent calls.

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 (start API key authorization) and immediately scopes it ('no existing API key needed'). It also names the follow-up sibling check_api_key_status, so an agent can distinguish this initiation step from the status-checking step without inspecting either schema.

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?

Explicit when-to-use and when-not-to-use guidance: use this when the user has no key, do not supply an email on the user's behalf, do not invent an email. It routes to the alternative (poll check_api_key_status), specifies the cadence ('at the supplied interval'), and states stop conditions ('stop if the request expires', 'never create new requests in a loop').

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