bilibili_video_download

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

No annotations are provided, so the description carries the full burden. It discloses that the tool automatically downloads and merges video/audio into MP4, and mentions the ffmpeg requirement and non-sharing warning. However, it does not mention potential issues like the need for a valid cookie for high-quality downloads, rate limits, or behavior on errors. The description provides adequate but not exhaustive transparency.

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 concise with two sentences and a warning line. It front-loads the primary purpose and then gives prerequisite and restriction. Minimal waste, though could be slightly more structured (e.g., bullet points) but not necessary. Efficient.

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?

Given no output schema and no annotations, the description should cover return values and failure behavior. It does not mention what the tool returns (e.g., file path) or what happens on error (e.g., missing ffmpeg). While parameters are well-documented in schema, the overall completeness for a download tool is lacking essential behavioral context.

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 100%, so the schema already documents each parameter (videoId, cid, quality, outputDir) with descriptions including defaults and notes (e.g., VIP requirement for 4K). The description text adds no additional parameter context beyond what the schema provides, meriting a baseline score of 3.

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 specific verb '下载' (download), resource 'B站视频到本地', and key actions: auto-download video+audio and merge to MP4 using ffmpeg. It distinguishes from siblings like bilibili_video_info or bilibili_video_danmaku which are non-download tools.

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 mentions a prerequisite (ffmpeg installed) and a usage restriction (personal backup only). However, it does not explicitly guide when to use this tool versus alternatives like bilibili_download_list for managing downloads or bilibili_video_info for metadata. The context is clear but lacks exclusions or comparisons.

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