youtube_search

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

No annotations are provided, so the description carries the full burden. It discloses a key behavioral trait: 'Costs 100 quota units per call — use sparingly.' This is real behavioral information beyond the schema. However, it doesn't describe the return format, pagination behavior, or error conditions, so there's some gap, but the quota disclosure is valuable and specific enough to merit a 4.

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 reasonably concise, front-loaded with the core purpose and cost warning before the parameter list. The cost warning is placed early which is appropriate. The parameter list is organized cleanly. No wasted sentences, though the cost note could arguably be its own preceding sentence. Efficient overall.

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?

This is a moderately complex tool (8 params) with no annotations and no output schema, so the description must do substantial work. It covers all 8 parameters with semantic detail, adds the cost constraint, and provides format examples. The main gap is not describing the return values (since there's no output schema), but for a search tool the return shape is fairly intuitive. The description is adequate-to-good for this complexity level.

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 fully compensate. The description documents each parameter with its type and even provides example values for query format ('ISO 8601', 'ISO 3166-1 alpha-2'), which is helpful beyond the bare schema. The 'max 50' constraint on max_results adds valuable semantic detail not present in the schema. This exceeds what the schema provides and compensates well for the 0% coverage.

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 'Search YouTube for videos, channels, or playlists' with a specific verb+resource+scope. It distinguishes from siblings like youtube_trending and youtube_search_suggestions since the scope (search across three content types) is explicit. The cost note adds useful context, though the purpose itself is clear but doesn't explicitly name alternative sibling tools for differentiation.

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 provides context by listing all parameters and the cost warning ('use sparingly'), which implies a cost-conscious usage constraint. However, it doesn't explicitly state when to use this vs alternatives like youtube_list_videos, youtube_trending, or youtube_search_suggestions, nor does it provide exclusions or prerequisite conditions (e.g., whether auth is needed). Usage guidance is implied rather than explicit.

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