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YouTube MCP

YouTube MCP

by pratikgh0se
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Local

youtube_create_comment

Destructive

Create a top-level comment as the selected channel on a video that channel owns; comments on other videos are refused until ownership is verified.

Instructions

Create a top-level comment as the selected channel, only on a video that channel owns (replies on your own videos); other videos are refused with ownership_required.

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>",
      "text": "<text>"
    },
    "name": "youtube_create_comment"
  }
}

Input Schema

NameRequiredDescriptionDefault
textYesText of the new top-level comment.
confirmNoMust be true to perform this write; set it only after the user approved the action.
videoIdYesID of a video on the selected channel to comment on.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed3 schema fields changedv0.3.1
    • addedInput schema / properties / confirm / description
      Added value: +"Must be true to perform this write; set it only after the user approved the action."
    • addedInput schema / properties / text / description
      Added value: +"Text of the new top-level comment."
    • addedInput schema / properties / videoId / description
      Added value: +"ID of a video on the selected channel to comment on."
  2. First observedv0.1.0

TDQS

A4.1/5.0
Behavior4/5

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

Annotations only supply destructiveHint=true; the description adds genuinely new behavioral context: the ownership precondition and the specific failure mode with its error code (ownership_required). It does not cover quota/rate-limit behavior or whether the comment publishes immediately, but for a write tool with thin annotations this is solid added value and consistent with destructiveHint.

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; the action, actor, and constraint come first. The parenthetical adds a slightly muddy clause rather than clarity, which keeps it from a 5.

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

Completeness4/5

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

For a 3-parameter write tool with no output schema and only destructiveHint annotation, the definition covers the key thing an agent needs to know before calling: the video must be owned or the call fails. Missing only secondary details like quota cost or resulting comment state.

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 coverage is 100% and the videoId property already says 'ID of a video on the selected channel', so the description's ownership note largely restates the schema. The confirm-gating parameter and the text constraints are left entirely to the schema. Baseline 3 is appropriate.

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 and resource (create a top-level comment) plus the acting identity (selected channel) and the scope restriction (only on owned videos). The word 'top-level' cleanly separates it from youtube_reply_to_comment in the sibling list.

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 a clear precondition for use — the video must be owned by the selected channel — and states what happens otherwise (refused with ownership_required). It never explicitly names youtube_reply_to_comment as the alternative for other videos, and the parenthetical '(replies on your own videos)' is ambiguous, so routing to the sibling still takes some inference.

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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