fetch_danmaku

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

No annotations exist, so the description carries the burden. It discloses the 'does not generate notes' boundary and the return structure, adding meaning beyond just 'fetch'. However, it lacks details on prerequisites like valid URL format or cookie requirements, though these may be less critical for a simple fetch.

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?

Three concise sentences front-load the main purpose and efficiently cover usage, return format, and sibling relationships. Every sentence earns its place without 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?

For a simple single-parameter tool with an output schema, the description is fairly complete: it states purpose, usage, alternatives, and non-side-effects. It could mention URL validation or error behavior, but the output schema likely covers return details, and the tool is straightforward.

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 has 1 parameter (video_url) with 0% description coverage. The tool description does not explicitly explain the parameter format or constraints, only implying it's a Bilibili video URL. The param name is self-explanatory but the description adds little beyond what the name suggests.

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 fetches Bilibili video danmaku summaries, with a specific verb and resource. It also differentiates from siblings by noting it doesn't generate notes and positioning itself as a preview/reference step.

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?

Explicitly says when to use (before generating notes for preview/reference) and provides alternatives: fetch_comments for hot comments, and generate_note's include_comments to combine both. This is clear contextual guidance.

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