Check sign-up approval

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

Annotations only flag readOnlyHint=false with no guidance, but the description carries the full behavioral load: it enumerates the three outcomes ('waiting' with a retry-after hint, the API key delivered once and needing to be saved, and 'expired'). That retry and one-time-display information is exactly what an agent cannot get from the structured fields.

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?

One compact block: context, precondition, action, then the three possible results in the order the agent will encounter them. Parenthetical clarifications ('shown once; save it', 'ask again after the number of seconds it gives') each prevent a concrete failure mode rather than 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?

With no output schema, the description must describe returns and it does so completely for all three states, including the retry cadence for the pending case. An agent has everything needed to call it and act on any response.

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 description coverage is 100% and the single requestId property is already documented as coming from signup_start. The description's 'Send the request_id' restates the schema without adding format, sourcing, or validation detail, so the baseline 3 applies.

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 makes the operation concrete: poll sign-up status after signup_start for the case where the user approves via email button rather than dictating a code. It implicitly distinguishes itself from signup_start and signup_verify, though the verb+resource framing ('check signup status') relies on the title rather than the prose.

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 states exactly when to call (after signup_start, when the person taps the approval button instead of reading a code) and the alternative path is named by contrast. There is no inference required to pick this over the sibling flow tools.

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