Adjust the mix gain (dB) for dialogue, music, sfx, or voiceover. Changes apply to every layer of that role at mix time and are undoable.
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 mixing bus. | |
| gain_db | Yes | Bus gain, dB; 0 = unity. |
Changes observed during successful MCP inspections.
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?
Beyond the annotations, the description discloses that the operation is recorded/undoable and that it folds into every layer of the role at mix time rather than editing individual clips. This adds meaningful behavioral context and does not contradict the idempotentHint or destructiveHint annotations.
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?
Three short sentences, with the core action and resource front-loaded. The role set, undoability, and mix-time behavior are all relevant, and there is no filler or redundant restating of the schema.
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 simple two-parameter tool with idempotent and non-destructive annotations, the description covers the role domain, the gain unit, undoability, and the mix-time effect across layers. The only gap is explicit guidance on when to choose this tool over related siblings, but that is a usage-guidelines concern rather than a completeness failure.
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 description coverage is 100%, with both parameters already documented, including the role enum and dB semantics with 0 = unity. The description restates the role set and gain concept but adds little new parameter-specific meaning beyond that.
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?
The description names a specific operation ('Set an audio role's mix gain'), enumerates the allowed role values, and clearly identifies the resource. It distinguishes itself from related sibling tools like set_role_flags by focusing on audio role gain in dB.
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?
The description provides clear context that the tool affects every layer of a role at mix time, implying it is the right choice for role-wide gain adjustment. However, it does not explicitly state when to use this tool versus alternatives or list any exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.