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

Annotations already indicate a safe read-only operation. The description goes beyond them by specifying the concrete payload content and that it is meant for a particular pipeline stage, adding genuinely useful behavior context without any contradiction.

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 short sentences, front-loaded with what the tool returns and ending with when to use it. No redundant phrasing, filler, or repetition of schema details.

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 simple one-parameter, read-only tool with a complete input schema and an output schema, the description provides all needed context: what is returned, what stage it belongs to, and a clear separation from other tools.

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?

There is only one parameter, applicationId, and the schema describes it fully with 100% coverage. The description does not discuss the parameter, but the schema already carries all necessary meaning, so the baseline of 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 clearly states what the tool returns: where to mail the wet-signed W-7 package, the envelope checklist, and the case reference. This distinguishes it from other ITIN tools focused on eligibility, quotes, or document uploads.

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?

The description gives an explicit trigger: 'Share when the pipeline reaches the mail step.' It provides clear context but does not mention when not to use it or name alternative tools such as itin_mark_itin_documents_mailed.

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