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

Annotations already disclose readOnlyHint=true and destructiveHint=false, so the read-safe nature is known. The description adds a valuable guarantee—'the price shown is exactly what checkout charges'—which assures the agent that the quote is authoritative and consistent with downstream checkout. This goes beyond the annotation and adds meaningful behavioral context.

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 description is two sentences and starts with the primary output directly. The second sentence gives a critical usage note and a pricing guarantee. It is efficient with no filler; the only modest extra is the explanatory clause 'the tax id for founders without an SSN', which is useful context and not distracting.

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?

The output schema captures the return structure and annotations cover the read-only nature, but the description leaves the optional 'package' parameter unstated and does not explain its effect. Since the tool is simple and the enum makes choices obvious, the gap is not severe, but including package semantics would complete the picture for an agent that must decide the correct call.

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?

With schema description coverage at 0%, the description needed to compensate by explaining the 'package' parameter, but it does not mention 'package' at all. The enum values (ITIN_PACKAGE_PREPARATION, ITIN_PACKAGE_RENEWAL) are self-explanatory to a degree, but the description leaves the impact of package choice entirely up to the schema and does not clarify that both options yield different prices/timelines.

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 ('Returns') and a precise resource ('price and timeline for a U.S. ITIN application (IRS Form W-7)'), and ties it to founders without an SSN. It clearly distinguishes this from other ITIN tools like itin_check_itin_eligibility or itin_create_itin_checkout, though it doesn't name a sibling explicitly. The purpose is unmistakable.

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 instruction 'Quote this before offering the service' provides clear when-to-use guidance, but it does not explain when not to use it or compare it with alternatives such as itin_create_itin_checkout or itin_get_itin_application. It gives the intended usage context but lacks rejection/alternative routing.

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