download_douyin_media

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

No annotations provided. The description adds important behavioral details: handling of missing audio stream (video-only fallback) and security note about signed URLs. This compensates well for the absence of 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 sentences plus a bullet point; compact and front-loaded with the core action. However, the list of operations (stream-copy, mux, etc.) is somewhat dense and could be reorganized for readability.

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?

An output schema exists (not shown) but the description references a return field (media_mode) and warning, which helps. However, with 6 parameters and no explanations, the description is insufficient for full understanding of the tool's behavior.

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%. The description does not explain any of the 6 parameters (e.g., quality, filename, overwrite). The only indirectly related info is about audio stream handling, which does not clarify parameter usage.

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 action: download Douyin media, and lists specific operations (stream-copy mux, probe, decode-check, hash). It distinguishes from siblings which are URL resolution and probing.

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?

No explicit when-to-use vs alternatives; however, sibling tools have distinct purposes (resolve URL, probe media), making usage somewhat implied. No exclusions or preconditions are mentioned.

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