ytdlp__list_subtitle_languages

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

With no annotations, the description carries the burden of behavioral disclosure. It states a key trait: "Outputs subtitle language codes and formats without downloading," indicating non-destructive behavior. It also mentions maxRetries and response mode. However, it omits details like network/internet requirements, potential errors, or authentication nuances beyond the optional cookies parameter, leaving significant behavioral aspects undisclosed.

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 well-structured with a clear opening sentence, a concise @remarks note, and organized @param entries. It stays focused and each piece of information earns its place, covering purpose, output behavior, and all parameters without unnecessary verbosity.

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 description covers the main purpose, parameter details, and the non-downloading behavior. However, since there is no output schema, it leaves the exact return format somewhat vague (e.g., whether codes are returned as a list, array, or structured JSON). It also does not provide examples or error-handling notes, so it is not fully complete for a standalone tool description.

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 input schema has 0% description coverage, but the description compensates fully. Each parameter is explained: url must start with http(s), cookies must be Netscape-format, proxy is given with an example, maxRetries is capped at 2 with a default, and __mcp_response_mode has its enum-like options described. This adds meaning far beyond the bare schema.

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: "List all available subtitle languages for a video URL using yt-dlp." It names the specific resource (subtitle languages for a video) and the scope (all available), and it differentiates itself from sibling tools like ytdlp__download_video_subtitles by explicitly noting "without downloading."

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 provides useful context about when to use this tool: it lists subtitle languages "without downloading," implying a pre-download inspection step. However, it does not explicitly name alternative tools or state when-not-to-use conditions, so it lacks the full exclusion guidance needed for a 5.

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