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

Goes well beyond the annotations: it discloses that the operation is free, that nothing is mailed or charged, that rendering takes a moment (latency), and that the reply names the proof — critical context for a non-idempotent write that produces no output 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?

Four short sentences, front-loaded with the WRITE classification and the core action, then cost, latency, and reply shape. The endpoint path is the only extra and is genuinely useful for mapping to the HTTP API.

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 single-parameter write tool with no output schema, the definition covers the action, cost/side effects, latency expectation, and response shape. Nothing an agent needs to invoke it 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?

Only one parameter exists and schema coverage is 100% with a clear description ('Click2Mail job id (a draft)'). The prose's 'draft job' phrasing reinforces the constraint but adds no syntax or format detail beyond the schema, so the 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?

The description opens with a specific verb and resource ('render a proof (preview PDF) of a draft job') and constrains it to draft jobs. It also implicitly separates this from submission siblings by stating 'nothing is mailed or charged', so an agent can tell it apart from click2mail_submit_job.

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?

Usage is implied by 'draft job' and the free/no-mail caveat, which hints this belongs before submission. However, it never explicitly says when to use this vs. click2mail_submit_job, get_job_status, or get_job_info, nor when not to request a proof.

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