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

Annotations cover the safety profile (readOnly, non-destructive, closed-world), so the bar is lower. The description adds that entries include tags and thumbnails and how the id is consumed downstream, but says nothing about pagination, result size, or return format beyond the field hints.

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 tight sentences with the core purpose and the actionable next step front-loaded. No filler.

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 no-param list tool with annotations covering safety and no output schema, the description provides what's needed: what the library is, when to reach for it, and how to use results. Minor gap: no naming of the seam versus other list_* character tools.

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?

Zero parameters, so the baseline is 4. There is nothing to document and the description appropriately offers no parameter guidance.

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?

States a specific verb and resource (list VidGuy's preset character/actor library) and adds differentiating detail: it's a preset library with tags and thumbnails for UGC video. However, it doesn't explicitly distinguish itself from siblings like list_characters or list_seedance_library, so an agent must infer the boundary.

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?

Gives a clear condition for use: 'when you don't have your own character,' and instructs how to use a result ('Use a library entry's id as the UGC character'). It doesn't name alternative tools (e.g., list_characters) or state when NOT to use it, but the context is strong.

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