字幕 / 文字稿

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

Annotations already declare readOnlyHint and openWorldHint, but the description adds genuinely new behavioral context: AI subtitles typically require a login Cookie, and omitting lang switches the tool into a listing mode rather than a fetch mode. It does not cover error behavior or rate limits, so not a 5.

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?

One dense paragraph, front-loaded with the core action and followed by format guidance, the lang-omission rule, and the cookie caveat in priority order. Slightly packed, but no sentence is 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?

With no output schema, the description correctly compensates by describing the text return format, and it flags the auth prerequisite for AI subtitles. Page/multi-P selection and save behavior are left to the schema, which covers them adequately.

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 coverage is 83%, so the baseline is 3, but the description adds meaning the schema lacks: the concrete output shape of format=text ('[mm:ss] 台词') and the semantic effect of omitting lang. This is real value beyond the enum and per-param descriptions.

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 (获取视频字幕, including AI-generated) and immediately clarifies the return shapes for each format. An agent can distinguish it from siblings like bili_danmaku, bili_chapters, or bili_video_info without opening the schema.

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 actionable selection guidance: format=text is recommended for AI summarization/translation, while srt/ass/json should be saved as files. It also explains the special 'input only, no lang' case that enumerates available languages. No explicit sibling exclusion is offered, so it stops short of a 5.

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