Capture MIDI that was played recently (like Ableton's Capture feature).
AI agents use capture_midi to create or update resources in Ableton — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Ableton environment.
This tool creates/writes new MIDI data into the session by capturing recent MIDI input, similar to Ableton's built-in Capture feature. It modifies the session state by adding content but is fully reversible (the captured clip can be deleted). It does not execute arbitrary code, delete data irreversibly, or move financial resources, so Write is the appropriate category.
From the tool's definition The tool 'capture_midi' performs a 'Capture' operation in Ableton Live, which creates a new MIDI clip from recently played notes. This is a reversible creation operation ('Capture feature') with no destructive effects.
Documented attack patterns abuse exactly the kind of access capture_midi gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Ableton, and nothing reaches the server without passing your rules. This is the rule we recommend for capture_midi:
{
"version": "1",
"default": "deny",
"tools": {
"capture_midi": {
"limits": [
{
"counter": "capture_midi_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}capture_midi stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Capture MIDI that was played recently (like Ableton's Capture feature). It is categorised as a Write tool in the Ableton MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Ableton MCP server in PolicyLayer and add a rule for capture_midi: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Ableton. Nothing to install.
capture_midi is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the capture_midi rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for capture_midi. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
capture_midi is provided by the Ableton MCP server (jpoindexter/ableton-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Ableton, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
128 Ableton tools catalogued and risk-classified — across an index of 43,000+ MCP servers.