resend_send

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

Annotations only declare the generic profile (not read-only, open-world, non-idempotent, non-destructive); the description adds the non-obvious two-phase preview/approval workflow and the human-in-the-loop gate that an agent absolutely must know about. The pre-approved-recipient bypass is a real behavioral detail not derivable from annotations or schema.

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 the default (preview) mode stated first and the escalated (confirm) mode second. Every clause conveys actionable information; nothing is padded.

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 consequential outbound-send tool, the critical questions — does it actually send, and who approves — are answered, and an output schema covers return values. Remaining gaps are the untended body parameters (html vs text) and what the preview contains, which are secondary but not trivial.

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 0% across six parameters, so the description must carry the burden. It explains only `confirm` meaningfully; `to`, `subject`, `html`, `text`, and `reply_to` get no guidance, and it never says whether html/text are alternatives, whether both are allowed, or what happens if neither is supplied.

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 email from the configured sender') so an agent can immediately distinguish this from read-only siblings like resend_emails and resend_domains. It does not explicitly name the sibling it is not, but the write/send semantics make the boundary clear.

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 describes both operating modes: without confirm=true it returns a preview only; with confirm=true a human approval step is triggered. It also names the exception (pre-approved recipients) and an important constraint (the assistant cannot approve on the user's behalf), which is exactly the routing knowledge an agent needs before calling.

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