get_batch_mail_proof

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful non-schema behavior: the link expires in one hour, requires no API key, and is openable in any browser or IDE, plus it contrasts with the key-requiring API route.

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?

Single dense paragraph that front-loads the deliverable before the usage instructions, with no filler sentences. It is on the long side, but every clause (expiry, no key, sequencing, alternative) carries information.

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?

With an output schema present, return values need no explanation, yet the description still summarizes them. Usage, sequencing, and the sibling alternative are all covered; only error/permission edge cases are absent, which is minor for a read-only proof fetch.

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%, so batch_id and recipient are already fully documented with defaults and 1-based indexing. The description only implicitly touches the recipient parameter ('one recipient at its real size') and adds no format or syntax detail beyond the schema.

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 states a specific verb and resource ('a proof for the person checking the batch') and enumerates exactly what is produced: a one-hour PDF link of the template, the address label at real size beside the return address, plus the label lines as text. It is clearly distinguishable from siblings like get_batch_mail.

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 sequencing ('Call it after create_batch_mail and give the person proof_url before confirm_batch_mail') and names the alternative route ('links.proof on the batch is the API route itself and needs the API key') with the condition that selects it. Nothing about when to use this tool 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.