send_reply

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

With no annotations provided, the description carries the transparency burden. It discloses the confirmation flow, the fact that a later call actually sends, and that To is locked to the original Reply-To/From. It does not mention whether the first call has side effects, but the core behavioral safety information is present.

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 concise sentences deliver the essential workflow and constraints with no filler. The action is front-loaded, followed by the confirmation sequence and the To-lock caveat.

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?

The critical two-step confirmation behavior is covered, and the tool is usable as described. However, there is no output schema and the description does not mention the preview's contents, error/failure behavior, or how this relates to save_reply_draft/send_draft, leaving some gaps for an agent to infer.

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 only 33%, so the description must compensate. It does clarify confirm_token's role in the two-step flow and implies uid/body relate to the original message and reply content, but reply_all and account_id remain under-explained.

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 clearly identifies the action as preparing or SMTP-sending a reply and highlights the locked To field, which distinguishes it from siblings like send_email, send_forward, and save_draft. The two-phase nature is also stated upfront.

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 explicitly explains the required two-call workflow: first call gets a preview and confirm_token, second call with the token sends. It does not explicitly contrast with send_email/save_reply_draft, but the reply-specific context and confirmation gate give clear when-to-use guidance.

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