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

Goes far beyond the annotations by disclosing required scopes (email:read, email:send), enabled outgoing setup, that mail is submitted externally, the confirmation-form branch, and the full result taxonomy (awaiting_confirmation/review_url, accepted, sending, unknown, failed). It also resolves the apparent tension with idempotentHint=true by explaining that accepted/sending/unknown/failed are never retransmitted by repeating the call, and warns that 'unknown' may already have been delivered — context the annotations cannot carry.

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?

The high-stakes rule is front-loaded in the first sentence and every subsequent sentence covers a distinct concern: prerequisites, confirmation branch, retry safety, verification, and the sibling alternative. It is dense and long, but for a send action with no output schema the length is largely earned; a few clauses about the confirmation form could be tightened.

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?

No output schema exists, and the description compensates by enumerating the possible results and what each means for the agent's next action, including the caveat that 'accepted' is provider acceptance only, not recipient delivery. Auth requirements, failure semantics, and the retry path are all covered.

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% and the single draft_id parameter is already documented thoroughly, including its origin from prepare_email_draft and the confirmation requirement. The description adds confirmation-flow context but no new meaning about the parameter itself, so 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?

States a specific verb and resource ('Send an exact draft') plus the governing constraint ('once the owner confirms it; never approves on its own'), which immediately separates it from prepare_email_draft and get_email_draft. An agent can distinguish it from all 16 siblings without opening a 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?

Explicitly routes to the alternative: 'Use get_email_draft to check status without sending,' and names sent_check for verification after accepted/unknown. It also prescribes the exact follow-up path when the call returns awaiting_confirmation (confirm via review_url, then call again) and the exclusions for retransmission.

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