Simpler.Asia

studio.add_audio_to_timeline

Place an audio asset on a role track: 'audio-music' (background, default volume 0.3 — voice ducks music by role) or 'audio-voice' (narration, volume 1.0). It lands on the role's first track, or on the one track_id names (a second music bed, a second voice).

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>",
      "asset_id": "<asset_id>"
    },
    "name": "studio.add_audio_to_timeline"
  }
}

Input Schema

Name	Required	Description	Default
`track`	No		audio-music
`volume`	No	0-2; defaults 0.3 for music, 1.0 for voice.
`asset_id`	Yes
`track_id`	No	An audio track (vtr_) from get_composition; its role wins when track is left out. Defaults to the role's first track.
`project_id`	Yes	The studio project (vp_…) this tool acts on.
`start_time_ms`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 23, 2026

TDQS

A3.8/5.0

Behavior4/5

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

With only readOnlyHint=false provided, the description adds useful behavior beyond annotations: default volumes, music ducking by voice, placement on the role's first track, and track_id override behavior. It does not cover permissions or error cases, but the core mutation semantics are disclosed.

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?

Two tightly written sentences, front-loaded with the core action and then role details. Every phrase, including the ducking note and track_id caveat, earns its place.

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 mutation tool with no output schema and minimal annotations, the description covers the essential routing, role, and ducking behavior needed to call it correctly. Minor gaps remain around asset_id and start_time_ms semantics, but the key operational context is present.

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 only 50%, so the description carries extra burden. It meaningfully explains the 'track' role semantics and 'track_id' fallback, and reinforces volume defaults, but does not clarify asset_id or start_time_ms behavior beyond their schema names/defaults.

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?

The description states a specific verb and resource ('Place an audio asset on a role track') and explains the two role tracks with their behavior. It does not explicitly differentiate from close siblings such as studio.add_sound or studio.add_clip_to_timeline, but the role-based audio placement is clear.

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?

It implies usage through the role definitions (music vs. voice) and the track_id fallback, but never states when to use this tool instead of alternatives like add_sound or add_clip_to_timeline. The guidance is adequate but not explicit about alternatives or exclusions.

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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