list_available_transcripts

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 explicitly states 'Uses yt-dlp metadata only — no download,' which sets expectations about the tool's behavior and side effects (non-destructive, network-based). This adds useful behavioral context beyond the simple 'list' action, but it does not detail potential errors, rate limits, or authentication needs, which are minor for a read-only metadata operation.

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 two sentences, front-loaded with the core purpose, and includes only essential details. The behavioral note about no download is in the second sentence, which is appropriate as secondary information. There is no filler or repetition; every word adds value.

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 simple, single-parameter, read-only tool, the description is complete. It states what the tool does (lists caption tracks), what it returns (language codes and track types), and its behavioral boundary (no download). An output schema exists, so the description doesn't need to detail the return structure. The tool is simple enough that an agent won't need more to call it correctly.

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?

The parameter 'url' is a single string with no schema description. The description implies it's a video URL by saying 'a video URL exposes,' but the schema already indicates it's a URL through the property name. The description adds minimal semantic value, barely going beyond the schema. Since schema coverage is 0%, the description could do more, but the single, self-explanatory parameter makes up for it.

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 tool's purpose: 'List the caption tracks a video URL exposes' with specific details about what is listed (language codes and track type). It distinguishes itself from siblings like fetch_transcript, which retrieves actual transcript content, and video_info, which provides general metadata. The scope is well-defined and unambiguous.

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 implies usage: use this tool when you need to see available caption tracks without downloading them. It does not explicitly name when not to use it or alternatives, but the context with sibling tools makes it clear that for actual transcript content you'd use fetch_transcript. It lacks explicit exclusion but is clear enough for an agent to infer correct usage.

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