Find the least busy operational backend.
AI agents call least_busy_backend_tool to retrieve information from Qiskit Documentation MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries backend availability and queue status to identify the least busy one. It performs a read-only lookup of system state with no side effects, modifications, or execution of quantum circuits. The worst-case misuse is selecting a suboptimal backend, which has minimal blast radius.
From the tool's definition Tool name is 'least_busy_backend_tool' and description states 'Find the least busy operational backend.' This retrieves status/queue information about quantum backends without modifying any state or executing operations.
Attacks that exploit this kind of access
Find the least busy operational backend. It is categorised as a Read tool in the Qiskit Documentation MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Qiskit Documentation 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 Documentation 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 Documentation MCP Server MCP server (pypi:qiskit-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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