Retrieve transcript languages for a YouTube video using its 11-character video ID. Check which caption languages YouTube exposes before fetching transcripts.
List transcript languages for a YouTube video. Returns the transcript languages exposed by YouTube for a specific video.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | YouTube video ID (11-character code) |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries full burden for behavioral disclosure. While it states the tool is read-only and returns data, it doesn't mention idempotency, rate limits, error handling, or any potential side effects. The description is minimal, offering only basic functionality.
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 extremely concise, consisting of two clear sentences. Every word serves a purpose, making it easy for an AI agent to quickly understand the tool's function without extraneous detail.
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 the tool's simplicity (single parameter, no output schema, no nested objects), the description is largely complete. It covers the core function and expected output. Minor omission: no mention of error cases (e.g., invalid video ID), but for a straightforward list operation this is acceptable.
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 100% description coverage for the single parameter 'id', which is well-described as 'YouTube video ID (11-character code)'. The description adds no new semantic meaning beyond implying the video ID is needed. Hence 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 action 'List transcript languages' and the resource 'for a YouTube video'. It provides a concise definition that distinguishes this tool from siblings like youtube_transcript (which likely retrieves the transcript itself) and youtube_captions.
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?
No guidance on when to use this tool versus alternatives. For example, it doesn't suggest using it before calling youtube_transcript to check available languages. The description is purely declarative without usage context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.