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

Annotations already signal a non-read-only, non-idempotent action. The description adds useful behavior: each call resends the link, and the only blocked operation until confirmation is applying. It does not mention rate limits or side effects, but the added context is sufficient for such a simple tool.

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?

Two sentences with no wasted words. The first states the action, the second explains the relevant consequence. Information is front-loaded and directly supports tool selection and invocation.

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 zero-parameter tool with no output schema, the description is complete: it says what happens, to what target, and what effect it has on the user's workflow. An agent can call it correctly with no additional information.

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?

The tool has zero parameters, so there is nothing for the description to document. It still usefully identifies the implicit target as 'this account's address', which provides more semantic clarity than the empty 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: 'Send the email-confirmation link again to this account's address.' It's not a tautology of the title and clearly identifies this as the tool that resends the verification email, distinguishing it from account-management 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?

The description gives clear context: 'Applying is blocked until the address is confirmed; nothing else is.' This implies the tool is used when a user needs to unblock applying by resending verification, and no alternative sibling exists. It lacks explicit when-not-to-use guidance, but none is necessary here.

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