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

Annotations already declare openWorldHint=true and destructiveHint=false, so the bar is lower. The description still adds real context: an actual e-mail is dispatched outside the system, the resulting sign-up is pre-linked to the trainer, and the address should be verified beforehand. It omits whether invites can be re-sent, expire, or are rate-limited.

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 tight sentences with no filler; the core action is front-loaded and the safety caution follows. Every sentence earns its place.

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 simple two-parameter, no-output-schema tool, the description covers the action and one caution. It leaves open what the response contains, what happens if the address is already invited or already a student, and the meaning of the locale parameter.

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 0%, so the description must carry parameter meaning. It only implicitly documents the required 'email' field via 'address' and says nothing at all about 'locale', whose five enum values (pt_BR, en, es, fr, de) an agent must infer control the invitation e-mail's language.

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 concrete verb and resource: e-mails an invitation to sign up, and adds the key qualifier that the invite is already linked to the trainer. That distinguishes it from get_invite_link (retrieves a link) and create_student (creates a record), though it never names those siblings explicitly.

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?

Offers a precondition/caution ('Confirm the address with the person first') but no explicit when-to-use framing or alternatives such as create_student versus sharing an invite link via get_invite_link. Usage is implied rather than routed.

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