Send a draft

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

Annotations already disclose readOnlyHint=false, openWorldHint=true, idempotentHint=false, and destructiveHint=false. The description adds that the send is immediate, which is useful behavioral context beyond the annotations, though it does not discuss irreversibility, auth requirements, or after-send effects.

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 zero waste. The core action and the explicit-instruction constraint are front-loaded and easy to scan.

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?

Given 100% schema coverage, rich annotations, and no output schema, the description supplies the essential context: what it sends, by id, with source and an immediate-send warning. Minor omissions such as explicit differentiation from mail_send_email and any after-send behavior keep it from being fully comprehensive.

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 both optional parameters (from and account) and the required id are fully documented in the schema. The description adds only that the id comes from mail_create_draft or a drafts-folder search, which is helpful but does not meaningfully extend the other 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?

States a specific verb (Sends) and resource (an existing draft) scoped by id. It distinguishes drafting from the sibling mail_send_email by operating on an existing draft, and it names mail_create_draft as a source of the id.

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 condition for use: only on the user's explicit instruction. It also specifies that the draft id comes from mail_create_draft or a drafts-folder search. It does not explicitly compare this tool against mail_send_email or state when not to use it.

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