Find the least busy operational backend.
AI agents call least_busy_backend_tool to retrieve information from Qiskit Code Assistant MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Even though least_busy_backend_tool only reads data, uncontrolled read access leaks sensitive information and racks up API costs — an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Documented attack patterns abuse exactly the kind of access least_busy_backend_tool gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Qiskit Code Assistant MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for least_busy_backend_tool:
{
"version": "1",
"default": "deny",
"tools": {
"least_busy_backend_tool": {}
}
}least_busy_backend_tool is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Find the least busy operational backend. It is categorised as a Read tool in the Qiskit Code Assistant MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Qiskit Code Assistant MCP Server MCP server in PolicyLayer and add a rule for least_busy_backend_tool: 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 Qiskit Code Assistant MCP Server. Nothing to install.
least_busy_backend_tool is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the least_busy_backend_tool 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 least_busy_backend_tool. 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.
least_busy_backend_tool is provided by the Qiskit Code Assistant MCP Server MCP server (qiskit-code-assistant-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 71 Qiskit Code Assistant MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
71 Qiskit Code Assistant MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.