Stop a data stream (U64 only)
AI agents invoke ultimate_stop_stream to trigger actions in Commodore 64 Ultimate 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.
Stopping a data stream is an executable action that halts an ongoing operation on external hardware. While not destructive (it doesn't delete or permanently modify data) or write-like (it doesn't create or modify stored data), it actively changes the state of a running process. This falls into the Execute category as it triggers an external operation whose effects depend on which stream is being stopped.
From the tool's definition Tool name 'ultimate_stop_stream' and description 'Stop a data stream (U64 only)' indicate an operation that terminates an active process or resource on the Commodore 64 Ultimate hardware.
Documented attack patterns abuse exactly the kind of access ultimate_stop_stream gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Commodore 64 Ultimate MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for ultimate_stop_stream:
{
"version": "1",
"default": "deny",
"tools": {
"ultimate_stop_stream": {
"limits": [
{
"counter": "ultimate_stop_stream_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}ultimate_stop_stream 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.
Free to start. No card required.
Stop a data stream (U64 only). It is categorised as a Execute tool in the Commodore 64 Ultimate MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Commodore 64 Ultimate MCP Server MCP server in PolicyLayer and add a rule for ultimate_stop_stream: 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 MCP Server. Nothing to install.
ultimate_stop_stream is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the ultimate_stop_stream 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 ultimate_stop_stream. 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.
ultimate_stop_stream is provided by the Commodore 64 Ultimate MCP Server MCP server (martijn-devrev/ultimate64mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Commodore 64 Ultimate MCP Server, 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.
39 Commodore 64 Ultimate MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.