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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds valuable context beyond those annotations: the deprecation status, the likely empty/error response, and bulk execution support. No contradiction exists between the description and annotations.

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?

Two short, focused sentences deliver the core purpose, deprecation caveat, and bulk support without filler. The warning is front-loaded and every sentence contributes useful information.

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 handles the deprecation and bulk behavior well, which is the most important context for this tool. However, with four parameters, no output schema, and zero schema-description coverage, the missing parameter semantics leave the tool only partially documented for an agent.

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 for four parameters. It only explains the 'ids' parameter via the bulk-support statement, leaving 'id,' 'token,' and 'forUsername' semantically undocumented.

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 states 'Featured channels listed on a channel,' which clearly identifies the resource and the action. It also distinguishes itself from sibling channel-related tools by focusing on the featured-channels concept, though it could be more explicit with a verb like 'get' or 'fetch.'

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 strong context by noting that YouTube deprecated the featured-channels tab and that this route typically returns an empty/error envelope. This effectively warns the agent against expecting useful results, though it does not name a specific alternative tool.

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