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

Annotations already declare a safe, idempotent read, but the description adds what annotations cannot: the link expires in one hour, requires no key, and opens in any browser or IDE, plus that the record also returns label lines as text. The parenthetical contrasting links.proof as the API-key-required route preempts a likely wrong turn.

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 workflow instruction is front-loaded and the parenthetical caveat is well-placed. The first sentence is long and packs a list of PDF components that borders on over-specification, but every clause conveys something about the artifact being returned.

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?

An output schema exists, so return values need no prose, and the description still notes the label lines come back as text. Sequencing, expiry, auth-free access, and a disambiguation from the sibling route are all covered — nothing an agent needs in order to call this correctly is missing.

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 the 1-based recipient are already documented in the schema. The description reinforces 'recipient N's piece' but adds no format, default, or validation detail beyond what the schema states. Baseline 3 is appropriate.

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 concretely enumerates what the proof contains (PDF of the template as recipient N's piece prints, QR code, sample code, insert, plus the address label at real size) and explicitly contrasts it with the sibling-adjacent 'links.proof on the batch'. The verb is only implied, but the resource and its contents are unmistakable and no agent would confuse this with 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?

Explicit sequencing: 'Call it after create_batch_mail and give the person proof_url before confirm_batch_mail' tells the agent exactly where this sits in the workflow. It also names the alternative route (links.proof) and the condition that distinguishes them — that route needs the API key, this one does not.

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