ableton-mcp

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set_looper_state

Destructive

Set Ableton Looper State to Stop, Record, Play, or Overdub for a track and device; plan, confirm, and verify the observed state before guarded execution.

Instructions

Plan or request one exact native Looper State choice: Stop, Record, Play, or Overdub. Native execution rechecks the complete Looper, routing, and transport snapshot before writing State; result reports the immediately observed State parameter and whether it matches the target, not an audible or quantized-boundary outcome. Record/Overdub can mutate captured audio and cannot be rolled back by restoring a parameter value. This does not promise beat-scheduled execution; verify native quantization behavior separately.

Input Schema

Name	Required	Description
`dryRun`	No	False executes with token and hash.
`trackId`	Yes	ID from list_tracks.
`deviceId`	Yes	ID from list_devices.
`planHash`	No	Plan hash.
`targetState`	Yes
`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"
+  }
+]

Changed7 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 / deviceId / description

Previous value: -"Stable device ID returned by list_devices."New value: +"ID from list_devices."

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 / planHash / description

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

changedInput schema / properties / trackId / description

Previous value: -"Stable track ID returned by list_tracks."New value: +"ID from list_tracks."

changedOutput schema / (root)

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

First observedv0.1.0Sep 23, 2026

TDQS

A4.1/5.0

Behavior5/5

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

Goes well beyond the annotations: it discloses that native execution rechecks the full Looper/routing/transport snapshot before writing, that the result reports the immediately observed State and a match flag rather than an audible or quantized outcome, and that Record/Overdub mutate captured audio and cannot be rolled back by restoring a parameter value. That last point directly qualifies the destructiveHint=true annotation with the specific irreversibility mechanism.

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?

Four dense sentences, front-loaded with the action and target values, then risk and outcome semantics. Every sentence carries information, though the 'not an audible or quantized-boundary outcome' clause is wordy and could be tightened.

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 rich annotations and an output schema present, the description covers the risks and result semantics well. The main remaining gap is the two-phase plan/execute contract linking dryRun, planHash and confirmationToken, which an agent must infer from the schema alone.

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 86%, so the schema already documents all seven parameters including dryRun, planHash and confirmationToken. The description adds context for expectedStateVersion (the snapshot recheck/version precondition) but never explains the plan/token/hash relationship or that dryRun gates execution, so it adds only marginal meaning over the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource (set the native Looper State) and enumerates the exact allowed values Stop/Record/Play/Overdub. It also distinguishes itself from the read-only sibling context tools by framing the action as plan-or-request-a-write, so an agent can tell it apart from get_looper_performance_context without opening either schema.

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?

Usage is implied rather than stated: 'Plan or request' hints at a dry-run-then-commit workflow, and 'verify native quantization behavior separately' gives one caveat. However, no alternative tool is named (e.g. get_looper_performance_context to inspect state first), and there is no explicit when-not guidance.

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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