# least_busy_backend_tool

Find the least busy operational backend.

Agent View of the PolicyLayer registry record for `least_busy_backend_tool`. HTML page: https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/least-busy-backend-tool

## Facts

- Tool: `least_busy_backend_tool`
- Server: Qiskit IBM Transpiler MCP Server (`qiskit-ibm-transpiler-mcp-server`) — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server.md
- Install: `npx -y qiskit-ibm-transpiler-mcp-server`
- Homepage: https://github.com/Qiskit/mcp-servers
- Risk category: Read (Low risk)
- Registry record: grade F, identity verified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "least_busy_backend_tool",
    "arguments": {}
  }
}
```

## Why least_busy_backend_tool is rated Low

This tool queries backend status information to identify which quantum processor has the lowest queue depth or operational load. It is purely informational—it retrieves data about backend states without modifying system state, executing code, or triggering quantum operations. This is a typical Read category operation (search/query).

From the tool's own definition: "Tool name 'least_busy_backend_tool' and description 'Find the least busy operational backend' indicate a query operation that retrieves status/availability information about IBM quantum backends."

## Use case

AI agents call least_busy_backend_tool to retrieve information from Qiskit IBM Transpiler MCP Server without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Qiskit IBM Transpiler MCP Server:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "least_busy_backend_tool": {}
  }
}
```

## Other tools on Qiskit IBM Transpiler MCP Server (70)

- `cancel_job_tool` — Destructive — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/cancel-job-tool.md
- `delete_environment_tool` — Destructive — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/delete-environment-tool.md
- `delete_model_tool` — Destructive — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/delete-model-tool.md
- `delete_saved_account_tool` — Destructive — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/delete-saved-account-tool.md
- `ai_clifford_synthesis_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/ai-clifford-synthesis-tool.md
- `ai_linear_function_synthesis_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/ai-linear-function-synthesis-tool.md
- `ai_pauli_network_synthesis_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/ai-pauli-network-synthesis-tool.md
- `ai_permutation_synthesis_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/ai-permutation-synthesis-tool.md
- `ai_routing_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/ai-routing-tool.md
- `convert_qpy_to_qasm3_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/convert-qpy-to-qasm3-tool.md
- `generate_random_clifford_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/generate-random-clifford-tool.md
- `generate_random_linear_function_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/generate-random-linear-function-tool.md
- `hybrid_ai_transpile_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/hybrid-ai-transpile-tool.md
- `run_estimator_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/run-estimator-tool.md
- `run_sampler_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/run-sampler-tool.md
- `start_tensorboard_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/start-tensorboard-tool.md
- `start_training_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/start-training-tool.md
- `stop_tensorboard_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/stop-tensorboard-tool.md
- `stop_training_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/stop-training-tool.md
- `synthesize_clifford_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/synthesize-clifford-tool.md
- `synthesize_linear_function_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/synthesize-linear-function-tool.md
- `synthesize_permutation_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/synthesize-permutation-tool.md
- `transpile_circuit_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/transpile-circuit-tool.md
- `wait_for_training_tool` — Execute — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/wait-for-training-tool.md
- `analyze_circuit_tool` — Other — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/analyze-circuit-tool.md
- `batch_train_environments_tool` — Other — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/batch-train-environments-tool.md
- `compare_optimization_levels_tool` — Other — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/compare-optimization-levels-tool.md
- `create_clifford_env_tool` — Other — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/create-clifford-env-tool.md
- `create_linear_function_env_tool` — Other — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/create-linear-function-env-tool.md
- `create_permutation_env_tool` — Other — https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server/create-permutation-env-tool.md
- …and 40 more: https://policylayer.com/tools/qiskit-ibm-transpiler-mcp-server.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=qiskit-ibm-transpiler-mcp-server · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/qiskit-ibm-transpiler-mcp-server