Adjust a dialogue, music, SFX, or voiceover role's mix gain in dB; the undoable change applies across every layer of that role at mix time.
Set an audio role's mix gain (dB). role ∈ {dialogue,music,sfx,voiceover}. Recorded (undoable). Folds into every layer of that role at mix time.
| Name | Required | Description | Default |
|---|---|---|---|
| role | Yes | The audio role. | |
| gain_db | Yes | Role gain, dB; 0 = unity. |
Changes observed during successful MCP inspections.
v0.6.0Input schema / properties / gain_db / descriptionPrevious value: -"Bus gain, dB; 0 = unity."New value: +"Role gain, dB; 0 = unity."Input schema / properties / role / descriptionPrevious value: -"The mixing bus."New value: +"The audio role."v0.1.9Input schema / properties / gain_db / descriptionAdded value: +"Bus gain, dB; 0 = unity."Input schema / properties / role / descriptionAdded value: +"The mixing bus."v0.1.8Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare idempotentHint=true, destructiveHint=false and openWorldHint=false, and the description is consistent with them. It adds real context beyond the annotations: the change is "Recorded (undoable)" and it "Folds into every layer of that role at mix time," clarifying that the gain is applied non-destructively at mix rather than baked into layers. It still omits clamping/valid dB range and what state the call returns.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Four tight fragments with the core action front-loaded and no filler. The telegraphic style ("Recorded (undoable)") is compact but slightly clipped, and the mix-time note lands last where it is easy to skim past.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a two-parameter setter with no output schema, the description covers the action, target set, undoability and mix-time propagation, which is nearly everything an agent needs. Minor gaps remain around accepted dB range and whether a project session must be active.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so both parameters and the role enum are already fully documented in the schema, establishing a baseline of 3. The description's "(dB)" and the role set merely restate schema content; the one genuinely additive phrase, "folds into every layer of that role at mix time," describes effect rather than parameter meaning.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource ("Set an audio role's mix gain") and enumerates the valid roles, so the agent knows exactly which operation and domain this covers. It does not explicitly separate itself from the nearby sibling set_role_flags, leaving that distinction to be inferred from the noun (gain vs. flags).
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Usage is only implied: the fixed role enum tells the agent which targets are legal, and "at mix time" hints at when the value takes effect. There is no explicit guidance on when to choose this over set_role_flags or a per-layer gain tool, and no stated prerequisites such as needing an open project.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.