@aiwerk/mcp-server-elevenlabs

stream_chapter_snapshot_audio

Fetches audio for a chapter snapshot in ElevenLabs Studio, spending credits; returns MPEG bytes or saves to output_path.

Instructions

Stream Chapter Audio Spends ElevenLabs credits. Returns audio/mpeg bytes; pass output_path to save them.

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": {
      "project_id": "<project_id>",
      "chapter_id": "<chapter_id>",
      "chapter_snapshot_id": "<chapter_snapshot_id>"
    },
    "name": "stream_chapter_snapshot_audio"
  }
}

Input Schema

Name	Required	Description
`chapter_id`	Yes	The ID of the chapter.
`project_id`	Yes	The ID of the Studio project.
`output_path`	No	Where to write the returned bytes. Relative paths resolve against ELEVENLABS_OUTPUT_DIR. Omit it to get the data inline as base64 (small files only).
`convert_to_mpeg`	No	Whether to convert the audio to mpeg format.
`chapter_snapshot_id`	Yes	The ID of the chapter snapshot.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 13, 2026

TDQS

A3.7/5.0

Behavior4/5

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

Adds a genuine non-obvious cost warning ('Spends ElevenLabs credits') that annotations do not convey, and pairs it with the idempotentHint=false implication that repeated calls keep consuming credits. It also discloses the return format, which the absence of an output schema leaves otherwise unknown.

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?

Two short sentences, no filler, with the cost warning and return type front-loaded. Slightly marred by the clipped opening clause ('Stream Chapter Audio Spends ElevenLabs credits'), which reads as a truncated title fragment.

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?

With no output schema, the description carries the return-format burden and does it correctly (audio/mpeg bytes, saved or returned inline), plus the credit cost. It stops short of covering errors such as credit exhaustion or missing snapshot IDs.

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 all five parameters, including the ELEVENLABS_OUTPUT_DIR resolution and base64 fallback for output_path, are already documented. The description's output_path mention restates the schema rather than adding syntax or constraints, so the 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 (Stream) and resource (Chapter Audio) plus the return type (audio/mpeg bytes). An agent can distinguish it from stream_project_snapshot_audio_endpoint, though the description never names that sibling to make the distinction explicit.

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?

Gives operational guidance for one use case ('pass output_path to save them'), which implies streaming vs inline base64 handling, but never says when to choose this tool over get_chapter_snapshot_endpoint or the project-snapshot audio variant.

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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