Crawlora MCP

youtube_captions

Read-only

Fetch caption data for one YouTube video as timed text entries, optionally filtered by language. Use youtube_transcript for translation, JSON/text/SRT/VTT output, or timestamp controls; use youtube_transcript_languages to list available tracks.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "id": "<id>"
    },
    "name": "youtube_captions"
  }
}

Input Schema

Name	Required	Description	Default
`id`	Yes	YouTube video id.
`lang`	No	Caption language code (defaults to en).

Output Schema

Name	Required	Description	Default
`data`	Yes	The tool result payload (shape varies per tool; see each tool's docs resource).

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 7, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered and the bar is lower. The description adds that scope is a single video and that output is timed text entries, useful context beyond the structured fields, though it does not address auth, rate limits, or pagination.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences with zero waste: purpose is front-loaded, then the routing alternatives follow. Every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists so return values needn't be explained, and annotations cover the read-only/open-world profile. Purpose, scope, alternatives, and the language filter are all present, so nothing an agent needs to call it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, with both id and lang fully documented (including the 'defaults to en' behavior), so the schema does the heavy lifting. The description restates the language filter but adds no format or syntax beyond what the schema provides, making the baseline 3 correct.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (fetch) and resource (caption data) scoped to one YouTube video, and identifies the output form (timed text entries) plus the optional language filter. It names the two sibling tools it is not, so an agent can distinguish it from youtube_transcript and youtube_transcript_languages without opening either schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly routes the agent: use youtube_transcript for translation, JSON/text/SRT/VTT output, or timestamp controls, and youtube_transcript_languages to list available tracks. The condition that selects each alternative is stated rather than implied.

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

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