SiteCheck

Youtube Transcript

youtube_transcript

Read-only

A YouTube video's captions as plain text and timestamped segments, with the video's title, channel, duration, views, publish date, chapters and the list of caption languages. Accepts watch, youtu.be, shorts, embed and live links or the 11-character id; pick a language with lang (default English, else the first track). Auto-generated captions contain recognition errors. A video without captions is a 404 and not charged. Price: $0.01 in USDC per successful call, paid with x402 (Base, Solana or Arc); failed calls are not charged.

Input Schema

Name	Required	Description	Default
`url`	Yes	A YouTube link (watch, youtu.be, shorts, embed or live), or the 11-character video id
`lang`	No	Caption language code, e.g. en, de or pt-BR (optional)

Output Schema

Name	Required	Description	Default
`note`	No
`video`	No
`source`	No
`checkedAt`	No
`transcript`	No
`availableLanguages`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed20 schema fields changedOct 15, 2026
- removedInput schema / properties / id
```
Removed value: -{
-  "description": "The 11-character video id, instead of url",
-  "type": "string"
-}
```
- changedInput schema / properties / lang / description
```
Previous value: -"Preferred caption language code, e.g. en, de or pt-BR; default the video's original language"New value: +"Caption language code, e.g. en, de or pt-BR (optional)"
```
- changedInput schema / properties / url / description
```
Previous value: -"A YouTube link (watch, youtu.be, shorts or embed), or leave it out and use id"New value: +"A YouTube link (watch, youtu.be, shorts, embed or live), or the 11-character video id"
```
- addedInput schema / required
```
Added value: +[
+  "url"
+]
```
- addedOutput schema / properties / availableLanguages
```
Added value: +{}
```
- removedOutput schema / properties / channel
```
Removed value: -{}
```
- removedOutput schema / properties / durationSeconds
```
Removed value: -{}
```
- removedOutput schema / properties / method
```
Removed value: -{}
```
- removedOutput schema / properties / segmentCount
```
Removed value: -{}
```
- removedOutput schema / properties / segments
```
Removed value: -{}
```
- removedOutput schema / properties / segmentsTruncated
```
Removed value: -{}
```
- removedOutput schema / properties / text
```
Removed value: -{}
```
- removedOutput schema / properties / textChars
```
Removed value: -{}
```
- removedOutput schema / properties / title
```
Removed value: -{}
```
- removedOutput schema / properties / track
```
Removed value: -{}
```
- removedOutput schema / properties / tracks
```
Removed value: -{}
```
- addedOutput schema / properties / transcript
```
Added value: +{}
```
- removedOutput schema / properties / truncated
```
Removed value: -{}
```
- addedOutput schema / properties / video
```
Added value: +{}
```
- removedOutput schema / properties / videoId
```
Removed value: -{}
```
AddedOct 15, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Goes well beyond the readOnly/openWorld annotations: discloses that auto-generated captions contain recognition errors, that a captionless video returns 404, that only successful calls are charged ($0.01 USDC via x402 on Base/Solana/Arc), and that failures are free. These payment, failure, and data-quality caveats are exactly the non-obvious traits an agent needs.

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

Conciseness4/5

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

Front-loads the output content and then covers inputs, caveats, and pricing in tight sentences with no filler. The opening sentence is a long run-on list, but every clause carries selection-relevant information.

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?

For a paid, open-world tool with an output schema already covering return structure, the description still supplies the essentials an agent needs to call it correctly: input formats, language defaulting, the 404-on-no-captions case, and the billing model. Nothing material is left unspecified.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3, but the description adds real semantics not in the schema: lang defaults to English and otherwise falls back to the first available track, and it restates the accepted link formats for url. This enriches parameter behavior beyond the schema's field descriptions.

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?

Names a specific resource (a YouTube video's captions) and enumerates the exact outputs (plain text, timestamped segments, title, channel, duration, views, chapters, caption languages). An agent can immediately tell this is YouTube-specific and distinct from generic siblings like transcribe or media_transcript.

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

Usage Guidelines4/5

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

Gives clear input context (accepts watch, youtu.be, shorts, embed, live links or the 11-character id) and the language-selection rule (lang defaults to English, else the first track). It does not, however, explicitly route the agent away from siblings such as transcribe or media_transcript, so the when-not guidance is missing.

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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