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

Annotations already declare the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), so the description's job is supplementary. It adds genuinely non-obvious behavioral facts: no credit cost and operation during stealth mode, plus confirmation that the address is persisted to the waitlist. It doesn't discuss duplicate handling or response shape, but an output schema exists to cover the latter.

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 short sentences, front-loaded with the purpose before the cost/availability caveats. The middle sentence carries a bit of promotional weight ('Always free... stealth mode'), but each clause conveys usable selection 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 annotations, a fully documented schema, and an output schema present, the description covers what the agent must know to call it correctly. The only minor gap is the undocumented language parameter, which is unlikely to block a correct invocation.

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 3. The description restates email (required) and name (optional) but omits the 'language' parameter and its en/nl enum entirely, adding no meaning beyond the schema.

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: leaving an email address to be added to a waitlist for notification on reopening. This is unmistakably distinct from all siblings (idea generation, validation, B2B, credits), so an agent can select it without ambiguity.

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?

Gives clear situational context: use it when the platform is closed or in stealth mode, or when new access becomes available. It also notes it is free and consumes no credits, which implicitly routes the agent away from credit-spending siblings, but it never names an alternative tool explicitly.

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