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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, openWorldHint=false), and the description adds genuinely new context: the setup_token backing the 'ready' state is only valid for 24 hours. That expiry window is a real behavioral constraint an agent needs. It stops short of describing polling cadence or what happens after expiry beyond the 'expired' label.

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?

A single sentence, front-loaded with the returned values and each one glossed inline. No wasted text. It reads as a return-value spec rather than a purpose statement, which slightly hurts orientation but is efficient overall.

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 one required parameter, no output schema, and rich annotations, the description covers the main gap — the meaning of each return state — which is exactly what an output-less tool needs. The remaining omission is what the agent should do next on each state (retry, wait, restart signup).

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 the single parameter is documented as coming from create_account, so the baseline is 3. The description adds meaning beyond the schema by attaching a 24-hour lifetime to the setup_token, which tells the agent the token is time-limited rather than static.

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 enumerates the three return states (pending_email, ready, expired) which makes the tool's job — reporting account-confirmation state — unambiguous, and the title supplies the verb 'check'. It doesn't explicitly contrast itself with create_account or verify_installation, but the resource (account confirmation status) is distinct enough to separate it from siblings.

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?

Usage is only implied: the 'pending_email ... has not finished the confirmation page yet' phrasing hints at polling after create_account before running onboarding tools. There is no explicit statement of when to call this versus create_account or verify_installation, nor whether repeated polling is expected.

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