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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the safety profile is covered. The description adds real value beyond them: the resend_after throttle window, the requirement to keep the token private, and the explicit negative side effects (no account creation, no expiry extension).

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: the action first, then the token-handling constraint, then the explicit non-effects. No filler, and the most important routing information is front-loaded.

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?

For a one-parameter tool with no output schema and annotations that already cover the safety profile, this is nearly complete: it covers the action, the constraint, and the boundaries of the side effects. It does not say what the response looks like or what happens if the signup is no longer pending, which are minor gaps.

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 already documented, so the baseline is 3. The description adds a handling constraint for it ('Keep the signup token private') that the schema does not state, which is a genuine increment; the reference to 'resend_after seconds' as a non-schema value is mildly confusing but reads as server-side configuration.

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 gives a specific verb and resource: resending an email verification code for a pending signup, scoped to a token. The closing clause ('Does not create an account or extend the signup expiry') implicitly distinguishes it from revdoku_signup and revdoku_signup_verify, though no sibling is named outright.

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 implied by 'pending signup' and the resend_after throttle, so an agent can infer this is for a signup that already exists but hasn't verified. However, no alternative tool is named and there is no explicit when-not guidance (e.g., what to do if the signup already expired or was verified).

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