Download a Bilibili video's audio track at the lowest bitrate to save data, providing audio files for transcription or other uses.
直连下载视频的音频轨（m4s，选最低码率省流量）。为 asr_transcribe 备料； 需要完整音频文件时也可用 batch 工具或 bili-subtitle CLI 的 --audio。
| Name | Required | Description | Default |
|---|---|---|---|
| p | No | ||
| output_dir | No | ./out | |
| url_or_bvid | Yes |
Changes observed during successful MCP inspections.
v0.2.0Does 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 the format (m4s) and bitrate selection (lowest to save traffic), but does not mention potential side effects like creating files, needing authentication, or possible failure modes. It is not contradictory, but it lacks depth for a tool without annotation support.
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, two sentences, with the primary purpose front-loaded and the alternative usage clearly appended. Every sentence adds value 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?
The tool is simple (downloads audio) and has no output schema, but given the 0% schema coverage and no annotations, the description should cover parameter semantics and possibly error conditions. It does mention the primary use case and alternatives, but omits crucial parameter explanations and any behavioral caveats. It is adequate but not comprehensive.
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%, and the description does not explain any of the three parameters (p, output_dir, url_or_bvid). While output_dir and url_or_bvid are somewhat self-explanatory, 'p' is ambiguous (likely a page or part index) and remains unexplained. The description fails to compensate for the lack of parameter documentation.
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 states a specific verb and resource: '直连下载视频的音频轨' (directly download the audio track of a video), with format m4s and lowest bitrate. It also explains its role as preparation for asr_transcribe, clearly distinguishing its purpose from that of other tools like batch_download_subtitles or the CLI.
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?
It explicitly states when to use this tool (for asr_transcribe preparation) and when not to (when a complete audio file is needed, use the batch tool or the CLI's --audio option). This provides clear guidance and names alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.