youtube_get_channel_details

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

No annotations are provided, so the description carries the full burden. The verb 'Fetch' implies a read-only operation, and the listed fields give a sense of the response, but there is no mention of quota usage, error behavior, or rate limits. Adding some context about these aspects would improve the score.

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 long, front-loaded with the core action and resource, and the second sentence adds valuable usage context without redundancy. No filler words or unnecessary explanations.

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 description explains what the tool returns (subscriber count, total views, etc.) and why it's useful, covering enough to operate effectively. It does not explicitly mention the input parameter or error scenarios, but the schema covers the input, and the tool is simple enough that this description is sufficient. Slightly more detail on output format or edge cases would push it to a 5.

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 coverage is 100%, so the parameter 'channelIds' is already well-described in the schema (array, max 50). The description itself does not add parameter-specific details but does reinforce the overall purpose. Baseline 3 is appropriate given the schema's completeness.

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 identifies the tool as fetching channel metadata and lists specific fields (subscriber count, total views, video count, creation date). It distinguishes from siblings by focusing on 'channels' rather than videos or niches, but does not explicitly compare or contrast with alternatives.

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 a clear use case (understanding competitive landscape, assessing channel sizes) but does not mention when not to use it or explicitly name alternative tools. This counts as clear context without exclusions.

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