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

With no annotations, the description carries the full burden of behavioral disclosure. It only states the action and adds billing/group info, but does not describe return format, pagination behavior (despite a nextToken parameter), whether results are limited, or any side effects. This is insufficient for an agent to understand the tool's behavior beyond 'it searches'.

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: two short sentences with no wasted words. It front-loads the primary purpose and includes minimal operational context (group, billing). It is appropriately sized, earning a high score on conciseness.

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 the tool has 8 parameters, a pagination token, and no output schema, the description is far too sparse. It does not explain the query semantics, how filters like duration/features interact, or what the response contains. The billing/group info is minor context but does not fill the gap. This is inadequate for a tool of this complexity.

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 parameters with descriptions and enums. The tool description adds no additional meaning beyond what the schema provides, which is the baseline for this dimension. It does not explain parameter relationships or best practices, so it stays at baseline 3.

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's purpose: 'Searches for channels on YouTube.' It uses a specific verb (searches) and a resource (channels on YouTube), and distinguishes it from sibling search tools like search_video or search_playlist by explicitly mentioning 'channels'. This is unambiguous and differentiated.

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 other search-related siblings (e.g., get_youtube_v3_search_video, get_youtube_v3_search_playlist). It does not mention scenarios, exclusions, or alternatives, leaving the agent to infer usage from the name and schema alone.

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