ableton-mcp

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select_device_ab_slot

Destructive

Switch an Ableton device between native A/B comparison slots while preserving transport; guarded execution blocks unsafe states and verifies observed controls.

Instructions

Load exact native device A/B slot A or B while preserving transport. Binds current device identity/parameters and refuses recording, frozen owner or active/unknown automation. Switching can disable automation without re-enabling it on return. Reports observed slot/controls; no hidden preset, automation-preservation, phase or audible proof.

Input Schema

Name	Required	Description
`dryRun`	No	False executes with token and hash.
`trackId`	Yes	track-N from list_tracks, return-N from get_set_mixer, or master.
`deviceId`	Yes	ID from list_devices.
`planHash`	No	Plan hash.
`targetSlot`	Yes	Exact native comparison slot.
`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"
+  }
+]

Addedv0.3.0Oct 19, 2026

TDQS

A4.1/5.0

Behavior5/5

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

Annotations only declare destructive=true, readOnly=false, idempotent=false. The description goes well beyond that by disclosing the refusal conditions, warning that 'Switching can disable automation without re-enabling it on return,' and disclaiming hidden preset, automation-preservation, phase or audible proof. This is exactly the side-effect context an agent needs for a destructive mutation.

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?

Front-loaded with the core action and scope, then layered with refusals and caveats. Four dense sentences with little waste, though the disclaimer sentence is packed enough to be slightly hard to parse.

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?

An output schema exists, so return values need not be explained, and the description still notes it 'Reports observed slot/controls.' Combined with the refusal conditions and automation side-effect warning, an agent has enough to call it correctly; only the routing to a context/prerequisite tool is missing.

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 description coverage is 100%, so the schema already documents all seven parameters, and the baseline is 3. The description only loosely touches identity/parameter binding ('Binds current device identity/parameters') without adding syntax or format meaning beyond the schema.

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?

States a specific verb and resource: 'Load exact native device A/B slot A or B while preserving transport.' An agent can distinguish it from read-only siblings like get_device_ab_context and the copy-oriented copy_device_ab_slot. It does not name a sibling explicitly, so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear when-not conditions: it 'refuses recording, frozen owner or active/unknown automation,' which tells the agent the preconditions that must hold. However it never routes the agent to a prerequisite sibling (e.g. get_device_ab_context) or names an alternative, so it is context without explicit alternatives.

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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