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

No annotations are provided, so the description carries the burden. It states 'Retrieves', implying a safe read operation, but does not disclose potential error behavior (e.g., invalid handle) or any side effects. The billing note adds context but not behavioral detail. A basic getter might be acceptable, but the transparency is minimal.

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 one concise sentence that communicates the core action and includes an example. It also mentions group and billing details without bloat. No redundant or unnecessary text.

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?

For a simple one-parameter getter with no output schema, the description is sufficient: it states the return value (channel ID) implicitly and the input. It could mention error handling, but given the low complexity, the information provided is adequate for an agent to use the tool correctly.

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?

The schema already provides full coverage for the single parameter 'handle' (type, example, description). The description repeats the example and adds no additional meaning beyond the schema. Baseline 3 is appropriate given 100% schema description 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 explicitly states the tool's function: 'Retrieves the channel ID for a given YouTube handle', with a concrete example ('@MrBeast'). This clearly distinguishes it from sibling tools that handle other resources like videos, posts, or playlists.

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 purpose implicitly defines when to use it: whenever you have a YouTube handle and need its channel ID. While it doesn't explicitly mention alternatives or exclusions, the context is unambiguous and sufficient for a simple lookup tool.

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