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

Annotations already declare destructiveHint=true, openWorldHint=true, idempotentHint=false and readOnlyHint=false, so the safety profile is known. The description still adds real value: the email is actually sent unless cancelled in the Cyberimpact app before send_at, and a mailing cannot be deleted through this server. It does not describe what the call returns (e.g. a mailing ID) or failure/partial-group behavior.

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?

Front-loaded with the write/send warning, then preconditions and the deletion caveat, with no filler. The 'POST /mailings' tail is mildly extraneous but harmless.

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 an 11-parameter destructive send with no output schema, the description covers the key risks (real send, cancellation window, non-deletable, sender validation, approval gate). Remaining gap is the response contract and what happens on scheduling failure, minor given the schema's thoroughness.

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 100%, so every parameter including send_at timezone, language enum, group_ids and confirm_send is already documented. The description only restates confirm_send=true and mail_from validation, adding no syntax or format detail the schema lacks, so it sits at the baseline.

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 (create a mailing scheduled to be sent at send_at), the resource, and the recipient scope (every member of the chosen groups). The 'WRITE, SENDS EMAIL TO CUSTOMERS' lead makes it unmistakably a mutating send tool, distinct from the read/list siblings like cyberimpact_get_mailing and cyberimpact_list_mailings.

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?

Explicitly gates usage: only after the user has approved subject, body, sender and groups, and confirm_send must be true. It also states the prerequisite that mail_from be a validated sender and the cancellation window, so an agent knows both when to call and what must be true beforehand.

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