YouTube Data MCP Server

getCommentReplies

Fetch all replies to a YouTube comment by providing the repliesToken from a getComments response.

Instructions

Fetch replies to a specific YouTube comment. Use repliesToken from getComments response.

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": {
      "pageToken": "<pageToken>"
    },
    "name": "getCommentReplies"
  }
}

Input Schema

Name	Required	Description	Default
`pageToken`	Yes	repliesToken from a comment object

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Aug 10, 2026

TDQS

A3.9/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions the token source but does not disclose response format, pagination, error behavior, or any side effects. For a tool with no annotations, this is a significant gap.

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?

The description is two short sentences, each earning its place. It is front-loaded with the main verb and resource, and the second sentence provides a necessary usage hint. No wasted words.

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

Completeness3/5

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

The tool is simple with one parameter and no output schema, but the description does not specify the return format or any pagination limits. It does establish the key integration step (using repliesToken from getComments), which is essential context. However, for a tool without an output schema, the description could be more explicit about what is returned.

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?

The parameter schema already provides 100% coverage for pageToken with a clear description. The description adds value by linking the token to getComments response, reinforcing the meaning beyond the schema. This extra context justifies a score above the baseline of 3.

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?

The description uses a specific verb ('Fetch') and resource ('replies to a specific YouTube comment'), which clearly distinguishes it from siblings like getComments (top-level comments) and getTranscript. The purpose is unambiguous and directly communicates the tool's function.

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?

The instruction 'Use repliesToken from getComments response' provides clear context on how to use the tool, implying it should be called after getComments. It does not explicitly state when-not-to-use or name alternatives, but the dependency on getComments is clearly conveyed.

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

Deploy Server