YouTube Media Downloader

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions 'pagination scraping is supported' which adds some context about how results are returned, but doesn't describe what the tool returns (channel objects? metadata?), error conditions, rate limits, authentication requirements, or whether it's a read-only operation. For a search tool with zero annotation coverage, this leaves significant behavioral gaps.

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 extremely concise with just two sentences that both add value. The first sentence states the core purpose, and the second adds important behavioral context about pagination. There's zero wasted text or redundancy.

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?

Given that there are no annotations and no output schema, the description should do more to compensate. While it's concise, it doesn't explain what the tool returns (channel data format), error handling, typical use cases, or how it differs from sibling tools. For a search tool with 4 parameters and no structured output documentation, this leaves the agent with insufficient context.

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 100%, so the schema already documents all 4 parameters thoroughly. The description adds no additional parameter information beyond what's in the schema. According to the rubric, when schema coverage is high (>80%), the baseline is 3 even with no param info in the description.

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 searches for YouTube channels with 'searches for YouTube channels', which is a specific verb+resource combination. However, it doesn't explicitly differentiate from sibling tools like 'search_for_channel_videos_and_playlists' or 'search_for_playlists', which also perform searches but for different resource types.

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 no guidance on when to use this tool versus alternatives. It mentions pagination support but doesn't specify when to use this search tool over other search tools (like for videos or playlists) or when to use it versus list tools for channels. There's no mention of prerequisites, limitations, or typical use cases.

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