ableton-mcp

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set_master_mixer

Destructive

Set Ableton Live Main volume, pan, cue volume, crossfader, and output channel with guarded confirmation, automation checks, and deferred readback.

Instructions

Guard Main volume, Stereo pan, cue, crossfader and exact hardware-channel edits with native identities, recording/automation checks and deferred readback. Binds Main controls, routes and crossfader membership. Partial writes remain without rollback or replay; inspect verified and writes. Mix-wide scope required.

Input Schema

Name	Required	Description
`pan`	No	Main pan.
`dryRun`	No	False executes with token and hash.
`volume`	No	Main volume.
`planHash`	No	Plan hash.
`cueVolume`	No	Cue volume.
`crossfader`	No	Crossfader position.
`outputChannelId`	No	Exact available Main output channel ID from get_set_mixer.
`confirmationToken`	No	Single-use plan token.
`expectedStateVersion`	Yes	Observed stateVersion.

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv0.3.1Oct 23, 2026

removedOutput schema / additionalProperties
```
Removed value: -true
```

addedOutput schema / anyOf

Added value: +[
+  {
+    "oneOf": [
+      {
+        "properties": {
+          "confirmation": {
+            "properties": {
+              "expiresAt": {
+                "type": "number"
+              },
+              "planHash": {
+                "pattern": "^[a-f0-9]{64}$",
+                "type": "string"
+              },
+              "token": {
+                "minLength": 1,
+                "type": "string"
+              }
+            },
+            "required": [
+              "token",
+              "planHash",
+              "expiresAt"
+            ],
+            "type": "object"
+          },
+          "dryRun": {
+            "const": true
+          },
+          "plan": {
+            "type": "object"
+          }
+        },
+        "required": [
+          "dryRun",
+          "plan",
+          "confirmation"
+        ],
+        "type": "object"
+      },
+      {
+        "properties": {
+          "dryRun": {
+            "const": false
+          },
+          "operationOutcome": {
+            "properties": {
+              "evidence": {
+                "items": {
+                  "type": "string"
+                },
+                "type": "array"
+              },
+              "reason": {
+                "type": "string"
+              },
+              "schemaVersion": {
+                "const": 1
+              },
+              "status": {
+                "enum": [
+                  "applied",
+                  "outcome_unknown",
+                  "postconditions_failed",
+                  "pending_postconditions",
+                  "pending_user_action"
+                ]
+              }
+            },
+            "required": [
+              "schemaVersion",
+              "status",
+              "reason",
+              "evidence"
+            ],
+            "type": "object"
+          }
+        },
+        "required": [
+          "dryRun",
+          "operationOutcome"
+        ],
+        "type": "object"
+      }
+    ],
+    "properties": {
+      "dryRun": {
+        "type": "boolean"
+      }
+    },
+    "required": [
+      "dryRun"
+    ],
+    "type": "object"
+  },
+  {
+    "properties": {
+      "error": {
+        "properties": {
+          "message": {
+            "type": "string"
+          },
+          "outcome": {
+            "enum": [
+              "unknown",
+              "not_executed"
+            ]
+          }
+        },
+        "required": [
+          "message",
+          "outcome"
+        ],
+        "type": "object"
+      }
+    },
+    "required": [
+      "error"
+    ],
+    "type": "object"
+  }
+]

Changed8 schema fields changedv0.3.0Oct 19, 2026

changedInput schema / properties / confirmationToken / description

Previous value: -"Short-lived, single-use token returned by the matching dry run."New value: +"Single-use plan token."

changedInput schema / properties / dryRun / description

Previous value: -"Omit or true to return a plan; false requires a valid confirmationToken."New value: +"False executes with token and hash."

changedInput schema / properties / expectedStateVersion / description

Previous value: -"Exact stateVersion observed immediately before planning."New value: +"Observed stateVersion."

changedInput schema / properties / outputChannelId / description

Previous value: -"Exact available master output channel ID from get_set_mixer."New value: +"Exact available Main output channel ID from get_set_mixer."

changedInput schema / properties / pan / description

Previous value: -"Master pan."New value: +"Main pan."

changedInput schema / properties / planHash / description

Previous value: -"Hash returned by the matching dry run."New value: +"Plan hash."

changedInput schema / properties / volume / description

Previous value: -"Master volume."New value: +"Main volume."

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "type": "object"
+}

First observedv0.1.0Sep 23, 2026

TDQS

A3.6/5.0

Behavior4/5

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

The description adds meaningful behavioral context beyond the annotations: it discloses that writes may be partial, that there is no rollback or replay, and that the caller should inspect verified writes. This is valuable for a destructive mutation tool, though terms like 'verified and writes' remain somewhat cryptic.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loads the affected controls, but it packs several dense concepts into short phrases such as 'native identities', 'recording/automation checks', and 'deferred readback'. It is not bloated, but the structure is less readable than it could be.

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 destructive, multi-parameter master mixer mutation with an output schema, the description covers the critical behavioral caveats: partial writes, no rollback/replay, and the need to inspect verified writes. It could be stronger by explicitly naming the prerequisite readback tool, but the schema already points to get_set_mixer.

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 100%, and every parameter already has a schema description, including Main volume, pan, cue volume, crossfader, output channel ID, token, hash, dryRun, and expected state version. The description reinforces the affected mixer areas but adds little parameter-specific meaning beyond what the schema already provides.

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 identifies the resource (Main/master mixer) and the controls affected: volume, stereo pan, cue, crossfader, and hardware-channel edits. It is more specific than the name alone, though the verb 'guard' and phrases like 'native identities' make the operation slightly less crisp than a direct 'set/update' statement.

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?

The description implies usage through 'Mix-wide scope required' and the focus on Main controls, which helps distinguish it from track- or return-scoped mixer tools. However, it does not explicitly say when to use this instead of siblings such as set_mixer_panning, set_crossfader_state, set_return_mixer, or set_track_mixer.

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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