youtube_get_categories

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

No annotations are provided, so the description carries the burden. It does disclose 'Costs 1 quota unit,' which is useful operational context. However, it doesn't describe return structure or behavior quirks — though with no output schema, this is a minor gap for a simple enumeration tool.

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 tight and efficient — clear purpose, two use cases, quota cost, and a parameter documented in under 40 words. Front-loaded with the purpose statement. Slightly formulaic with the Args section but no wasteful prose.

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 1-param enumeration tool with no output schema, the description is reasonably complete. It covers purpose, usage contexts, cost, and the parameter. However, it doesn't mention what the response contains (categories list format), and there's no output schema to fill that gap, leaving the return format somewhat ambiguous.

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 description coverage is 0%, so the description must compensate. It documents the region_code parameter well (format: ISO 3166-1 alpha-2, example 'US'), but the schema already conveys the name, default, and type. The description adds the format clarification and example, though not extensively beyond what the schema's 'Region Code' title hints at.

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 it 'lists available YouTube video categories for a region' — a specific verb+resource+scope. It doesn't explicitly distinguish from sibling tools, but the categories concept is reasonably unique among the variety of analytics/upload/comment tools present.

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 two concrete usage contexts: 'useful for filtering trending videos or setting video category on upload.' It doesn't explicitly exclude alternatives, but provides actionable when-to-use guidance that connects to related sibling tools like youtube_trending and youtube_upload_video.

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