send_draft

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

Annotations already declare destructiveHint=true and idempotentHint=false, so the safety profile is known; the description reinforces it with 'Irreversible' and adds genuinely new operational context about not blindly retrying after an unknown write outcome. It also discloses the return payload, which the absent output schema would otherwise leave unstated. Slightly short of 5 only because it does not describe auth/permission requirements.

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, front-loaded with the action and its result before the safety caveat and the prerequisite. Every sentence carries distinct, load-bearing information with no redundancy.

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 irreversible mutation with no output schema, the description covers action, return shape, irreversibility, call conditions, and the retry hazard. An agent has everything needed to invoke it safely, including the alternative that creates the draft.

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 account and draftId are already documented in-schema, including the caveat to use the top-level id rather than message.id. The description adds no further parameter-level meaning beyond pointing at create_draft, so the baseline 3 applies.

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?

'Send an existing draft and return the sent message {id,threadId,labelIds}' gives a specific verb, resource, and even the return shape, so the agent knows exactly what happens. It is clearly separable from siblings like create_draft or get_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?

Explicitly states the when ('only when the user explicitly asks to send this specific draft') and the when-not ('never to retry after write_outcome_unknown without checking Gmail first'), and points to the prerequisite tool create_draft. Nothing is left to inference.

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