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YouTube MCP

YouTube MCP

by pratikgh0se
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Local

youtube_set_thumbnail

Destructive

Set an approved thumbnail on an owned YouTube video using a local image and an approval ID, ensuring thumbnail changes occur only after explicit confirmation.

Instructions

Set an approved thumbnail on an owned video.

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": {
      "videoId": "<videoId>",
      "filePath": "<filePath>",
      "mimeType": "<mimeType>",
      "approvalId": "<approvalId>"
    },
    "name": "youtube_set_thumbnail"
  }
}

Input Schema

NameRequiredDescriptionDefault
confirmNoMust be true to execute; set it only after youtube_approve approved this exact preview.
videoIdYesID of an owned video to set the thumbnail on.
filePathYesAbsolute path to the local thumbnail image.
mimeTypeYesThumbnail MIME type: image/jpeg or image/png.
approvalIdYesApproval ID from the youtube_preflight_set_thumbnail preview, after approving it with youtube_approve.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed5 schema fields changedv0.3.1
    • addedInput schema / properties / approvalId / description
      Added value: +"Approval ID from the youtube_preflight_set_thumbnail preview, after approving it with youtube_approve."
    • addedInput schema / properties / confirm / description
      Added value: +"Must be true to execute; set it only after youtube_approve approved this exact preview."
    • addedInput schema / properties / filePath / description
      Added value: +"Absolute path to the local thumbnail image."
    • addedInput schema / properties / mimeType / description
      Added value: +"Thumbnail MIME type: image/jpeg or image/png."
    • addedInput schema / properties / videoId / description
      Added value: +"ID of an owned video to set the thumbnail on."
  2. First observedv0.1.0

TDQS

B3.1/5.0
Behavior2/5

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

Annotations already declare destructiveHint=true, and the description adds only that the video must be owned and the thumbnail approved – both already conveyed by the name and schema fields (videoId description, approvalId description). It does not disclose that this replaces any existing thumbnail, whether the prior thumbnail is recoverable, or the permission/quota implications of an image upload for a mutation with no output schema.

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?

A single front-loaded sentence with no filler or redundant restatement of the title. It is arguably too terse given the complexity of the tool, but nothing in it is wasted.

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

Completeness2/5

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

For a five-parameter mutation with only a destructiveHint and no output schema, the description leaves important things unsaid: the required preflight/approve sequence, that confirm must be true, and what a successful or failed call returns. An agent could not safely invoke this from the description alone; it has to read the schema to learn the workflow.

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%, so every parameter including confirm, approvalId, videoId, filePath, and the mimeType enum is already documented in the schema. The description adds no format, path, size, or ordering guidance beyond it, so baseline 3 applies.

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

Purpose4/5

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

States a specific verb and resource ("Set an approved thumbnail") and constrains scope to an owned video, which distinguishes it from read-oriented siblings like youtube_get_owned_video. It does not explicitly name youtube_preflight_set_thumbnail as the required predecessor, but "approved" gestures at the paired workflow.

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

Usage Guidelines3/5

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

The word "approved" implies that a preview/approval sequence must happen first, so usage is implied rather than stated. There is no explicit when-to-use/when-not, no mention that youtube_preflight_set_thumbnail + youtube_approve are the prerequisites, and no statement about what to do if no approval exists.

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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