Apply for an ITIN using IRS Form W-7: get the step-by-step process, required documents, timelines, and common mistakes. Available in English and Spanish.
How to apply for an ITIN (IRS Form W-7): the process, documents, timelines, and common mistakes — with the full guide URL. EN/ES.
| Name | Required | Description | Default |
|---|---|---|---|
| lang | No | Answer language: en (default) or es (Spanish) |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful context about the guide's content and mentions a full guide URL, but it does not clarify the return format, whether live/external data is fetched, or any limitations.
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 one efficient sentence that front-loads the tool's purpose and then lists the key content areas. There is no filler or redundant explanation, and the trailing 'EN/ES' is brief and useful for indicating language support.
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 informational tool with strong annotations, the description adequately covers the topic, language options, and the presence of a guide URL. It does not fully specify the return structure, but the content list and guide URL mention are sufficient for basic selection and invocation.
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?
The single parameter 'lang' is fully described in the schema with an enum and default note, and the description's 'EN/ES' only echoes that. The schema carries the parameter documentation burden, so the description adds no additional semantic value beyond baseline.
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 the tool provides instructions for applying for an ITIN via IRS Form W-7, listing specific content areas: process, documents, timelines, and common mistakes. It is specific about the resource, but it does not explicitly distinguish itself from sibling tools like get_guide or faq_lookup.
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?
No guidance is provided about when to use this tool versus its siblings such as faq_lookup, search_guides, or get_guide. The 'how to apply' phrasing implies a use case, but there are no explicit when-to-use, when-not-to-use, or alternative recommendations.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.