mail_send

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

Annotations already mark this as a non-read, non-destructive, idempotent operation, so the description's retry guidance and 'Uses your own mailbox; no router billing' add useful context beyond the structured data. It does not contradict any annotation, and the caution about never resending under a new ID is valuable.

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, with the core purpose first and supporting cautions after. Every sentence earns its place; no filler or redundant restatement of the schema.

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?

Output schema exists and the parameter names are intuitive, but the 0% schema coverage plus lack of account_id clarification and no guidance about drafts leave the description only minimally complete for the tool's complexity.

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%, yet the description only explains request_id (reuse for retries). Account_id, to, subject, body, cc, bcc, html, and reply_to receive no semantic help, which is a notable gap for an API with nine parameters.

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?

Description opens with 'Send an authorized email or Gmail reply,' providing a specific verb and resource. The verb 'send' clearly separates it from siblings like mail_create_draft and mail_read, so an agent can identify its role without opening the schema.

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?

It implies the tool is for sending new or reply emails, and adds retry guidance with request_id, but never states when to prefer this over mail_create_draft or mail_drafts. No explicit exclusions or alternative routing is given, so usage is mainly inferred.

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