realize_chord · Music21 Composer MCP: Risk & Policy

WHAT IT DOES

What realize_chord does on Music21 Composer MCP

AI agents use realize_chord to create or update resources in Music21 Composer MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Music21 Composer MCP environment.

WHY IT NEEDS A POLICY

Why realize_chord needs a policy

The tool appears to generate or expand chord voicings/realizations, which creates new musical content that can be saved or exported. This is reversible data modification (Write) rather than irreversible deletion or external code execution. Severity is medium because misuse could generate malformed audio data or corrupt MIDI workflows, but impact is limited to a single composition project.

From the tool's definition Tool name 'realize_chord' combined with context of music composition server and sibling tools like 'reharmonize' and 'export_midi' indicates this creates or modifies musical data. The description is empty, limiting certainty.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

realize_chord Rate-limited

realize_chord 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "realize_chord": {
      "limits": [
        {
          "counter": "realize_chord_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Music21 Composer MCP, so you can run agents against it safely.

FAQ

Questions about realize_chord

What does the realize_chord tool do? +

realize_chord. It is categorised as a Write tool in the Music21 Composer MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on realize_chord? +

Register the Music21 Composer MCP server in PolicyLayer and add a rule for realize_chord: 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 Music21 Composer MCP. Nothing to install.

What risk level is realize_chord? +

realize_chord is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit realize_chord? +

Yes. Add a rate_limit block to the realize_chord 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.

How do I block realize_chord completely? +

Set action: deny in the PolicyLayer policy for realize_chord. 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.

What MCP server provides realize_chord? +

realize_chord is provided by the Music21 Composer MCP server (viktorkelemen/music21-composer-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.