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

With no annotations, the description carries the full burden, and it is transparent about side effects: an email is sent to the user, a one-click approval link with a short code is involved, and the user must verify the code. It also discloses cost/credit terms and the follow-up polling behavior, going well beyond a generic 'request key' statement.

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?

The description is dense but efficient, front-loading the core purpose and then providing the necessary workflow details. The first sentence is long and packs in multiple pieces of information, but each clause contributes useful context, so it earns a strong score rather than a perfect one.

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?

There is no output schema, so the description must explain the interaction flow, and it does so thoroughly: email, code display, approval, polling, and free tier details. It is slightly implicit about where request_id and claim_secret come from — though clearly implied as outputs of this step — and does not describe error/timeout behavior, which prevents a perfect score.

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%, so the baseline is already strong. The description adds workflow context by tying email to the sign-up email and indicating that client_name identifies the requesting agent/app. It does not repeat schema details unnecessarily, but it also does not significantly deepen the meaning of either parameter.

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 states a specific action ('Start sign-up from inside the agent'), a clear resource (free API key), and the prerequisite (user's email address). It also distinguishes itself from the sibling claim_api_key by framing this as the initial request step that precedes claiming.

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 gives an explicit when-to-use workflow: call this first, show the user the code, then poll claim_api_key with request_id and claim_secret. It also clarifies that no existing API key is needed and that this call is free, which helps an agent decide to use it in the auth flow.

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