Send a draft

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

Even though annotations already include destructiveHint=true and idempotentHint=false, the description adds meaningful detail: the side effect on the drafts list, the irreversibility of sending, the duplicate-email risk on retry, and rate-limit constraints. This goes well beyond what structured fields convey.

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 sentences, each with a distinct job: state the effect and output, instruct pre-call verification, explain no-retry and outcome checks, and list rate limits. There is no filler; the length is justified by the destructive, non-idempotent nature of the tool.

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 one-parameter tool with no output schema, this description covers the returned id/threadId, the verification step, ambiguous-outcome handling, and sending limits. An agent has all the information needed to invoke it safely and detect whether it succeeded.

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 coverage is 100% and the schema already documents 'The draft id from list_drafts or create_draft output.' The description's mention of 'existing draft' and 'verify the content with get_draft' is more about behavioral context than parameter semantics, so it meets the baseline without needing to compensate.

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?

The description opens with a specific action and resource: 'Sends an existing draft exactly as it is stored, immediately and irreversibly.' It also states the concrete outcome (draft disappears, becomes a sent message with returned id/threadId), and the focus on 'existing draft' distinguishes it from send_message, which creates a new message.

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 gives explicit when-to-use guidance: verify with get_draft before calling and never retry after timeout or 5xx because duplicates cannot be unsent. It also names fallback checks, list_drafts and list_messages in:sent, plus daily sending limits, providing clear context for choosing between this tool and alternatives.

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