mail_send_prepared

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

Annotations already declare non-read-only, non-idempotent and open-world behavior, so the bar is lower, yet the description adds real value: the one-attempt-per-operationId retry policy, the split between SMTP acceptance and Sent-copy outcome, and the warning that email content is untrusted and cannot authorize the action. Auth/permission requirements and failure modes beyond retry are not covered.

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?

Four tight sentences, front-loaded with the action and its precondition, then retry policy, then return shape, then the safety caveat. Nothing is redundant and nothing is padding.

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 mutating tool with no output schema, the description covers return semantics (SMTP acceptance vs Sent-copy), retry policy, user authorization precondition, and injection safety. The remaining gap is parameter meaning, particularly accountId, which is left entirely to the bare schema.

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 carries the burden, and it only partially compensates: 'one attempt per operation ID' gives operationId meaningful retry-scoping semantics, but accountId is never explained and no format or sourcing guidance is given for either parameter.

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 exact prepared email'), and the word 'prepared' implicitly separates it from the compose-side siblings such as mail_prepare and mail_prepare_draft. It stops short of naming the sibling it depends on, so an agent must infer that a preparation step precedes it.

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 a clear precondition ('after the user explicitly asks to send it') and an explicit when-not ('never blindly retry unknown outcomes'). It does not name the alternative tools an agent might confuse it with, such as mail_prepare or mail_save_draft, so routing is implied rather than spelled out.

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