modplay_upload | PolicyLayer

WHAT IT DOES

What modplay_upload does on Commodore 64 Ultimate Computer MCP Server

AI agents invoke modplay_upload to trigger actions in Commodore 64 Ultimate Computer MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

THE RISK

High Risk

Why modplay_upload needs a policy

This tool both uploads a file (Write) and plays it (Execute — triggers an external operation on the C64 device). Per the rules, Execute is more severe than Write, so Execute is the correct classification. The blast radius is medium: it controls media playback on a physical device and uploads data to it, but has limited broader impact.

From the tool's definition Upload and play an Amiga MOD file... from the Commodore 64 Ultimate filesystem

Documented attack patterns abuse exactly the kind of access modplay_upload gives an agent:

POLICY

How to control modplay_upload

PolicyLayer is an MCP gateway — it sits between your AI agents and Commodore 64 Ultimate Computer MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for modplay_upload:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "modplay_upload": {
      "limits": [
        {
          "counter": "modplay_upload_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

modplay_upload stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

Create a free account and register Commodore 64 Ultimate Computer MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

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EXPLORE

Related tools and policies

More Commodore 64 Ultimate Computer MCP Server tools

Destructive reset_config_to_default Reset configuration to factory defaults Destructive machine_poweroff Power down the machine (U64 only) Execute drive_reset Reset a specific drive Execute machine_reset Send reset signal to the C64 Execute enter_basic_program Enter a BASIC program directly into C64 memory. Takes BASIC source code text, tokenizes it Execute machine_reboot Restart and reinitialize the Commodore 64 Ultimate device Execute run_crt_file Start a cartridge file from filesystem Execute run_crt_upload Upload and start a cartridge file (base64 or data URL encoded) on the Commodore 64 Ultimat

All 54 Commodore 64 Ultimate Computer MCP Server tools →

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Go deeper

High-risk tools in Commodore 64 Ultimate Computer MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about modplay_upload

What does the modplay_upload tool do? +

Upload and play an Amiga MOD file (pure base64 or data URL encoded) from the Commodore 64 Ultimate filesystem. It is categorised as a Execute tool in the Commodore 64 Ultimate Computer MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on modplay_upload? +

Register the Commodore 64 Ultimate Computer MCP Server MCP server in PolicyLayer and add a rule for modplay_upload: 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 Commodore 64 Ultimate Computer MCP Server. Nothing to install.

What risk level is modplay_upload? +

modplay_upload is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit modplay_upload? +

Yes. Add a rate_limit block to the modplay_upload 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 modplay_upload completely? +

Set action: deny in the PolicyLayer policy for modplay_upload. 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 modplay_upload? +

modplay_upload is provided by the Commodore 64 Ultimate Computer MCP Server MCP server (xphileby/c64u-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Commodore 64 Ultimate Computer MCP Server tool call.

Start from Commodore 64 Ultimate Computer MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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54 Commodore 64 Ultimate Computer MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.