Find the least busy operational backend.
AI agents call least_busy_backend_tool to retrieve information from Qiskit Gym 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 load metrics to help select an optimal backend for circuit execution. It is purely informational—it retrieves data about backend states with no side effects, no code execution, and no data modification. This is a classic Read operation.
From the tool's definition Tool name 'least_busy_backend_tool' and description 'Find the least busy operational backend' indicate a query operation that retrieves status information about available quantum backends without modifying, executing, or deleting anything.
Attacks that exploit this kind of access
Find the least busy operational backend. It is categorised as a Read tool in the Qiskit Gym MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Qiskit Gym 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 Gym 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 Gym MCP Server MCP server (qiskit-gym-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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