step · VICE C64 Emulator MCP Server MCP: Risk & Policy

WHAT IT DOES

What step does on VICE C64 Emulator MCP Server

AI agents invoke step to trigger actions in VICE C64 Emulator 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.

WHY IT NEEDS A POLICY

Why step needs a policy

The step tool executes CPU instructions in the VICE emulator context. While debugging-focused and operating within a contained emulator environment (lowering risk vs. real system access), it still triggers external operations whose effects depend on arguments (instruction count, stepOver behavior). This qualifies as Execute rather than Read.

From the tool's definition Tool description states 'Execute one or more instructions' and 'count: Number of instructions to execute', indicating it runs code/instructions in the C64 emulator environment.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

step Rate-limited

step 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.

View as policy code

policy.json

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

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches VICE C64 Emulator MCP Server, so you can run agents against it safely.

FAQ

Questions about step

What does the step tool do? +

Execute one or more instructions, then stop. Single-stepping is essential for understanding code flow and debugging. Options: - count: Number of instructions to execute (default: 1) - stepOver: If true, treat JSR as single instruction (don. It is categorised as a Execute tool in the VICE C64 Emulator 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 step? +

Register the VICE C64 Emulator MCP Server MCP server in PolicyLayer and add a rule for step: 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 VICE C64 Emulator MCP Server. Nothing to install.

What risk level is step? +

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

Can I rate-limit step? +

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

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

step is provided by the VICE C64 Emulator MCP Server MCP server (simen/vice-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.