# get-law

`station__crystalbook__get-law` · external (needs EXECUTION_BACKEND_URL configured) · domain `crystalbook` · pv-relevance `non-pv`

Retrieve a single Law of System Homeostasis (1–8). Returns the vice, virtue, deviation, correction, mechanism, and homeostatic principle. Use to study or apply a specific Law.

> **Note:** This tool routes through an external execution backend. If `EXECUTION_BACKEND_URL` is unset on the server, calls return JSON-RPC error `-32603 "Tool execution backend not configured"`. Tools with `backend: native` execute in-process and are always callable.

## Agent metadata

- `idempotent`: unknown
- `read_only`: unknown
- `expected_latency_ms`: unknown (not yet contract-tested)
- `cost_tokens_estimate`: unknown

## Input schema

- `number` *integer* (required) — Law number (1–8). 1=True Measure, 2=Sufficient Portion, 3=Bounded Pursuit, 4=Generous Witness, 5=Measured Intake, 6=Measured Response, 7=Active Maintenance, 8=Sovereign Boundary.

## Example call

```json
POST /api/mcp
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "station__crystalbook__get-law",
    "arguments": {
      "number": 0
    }
  }
}
```

## Related

- [/tools](/tools) — all 3062 tools
- [/tools/crystalbook__get-law](/tools/crystalbook__get-law) — HTML page
- [/tools/crystalbook__get-law/json](/tools/crystalbook__get-law/json) — JSON form (agent-friendly)
- [/api/mcp](/api/mcp) — endpoint
- [/AGENTS.md](/AGENTS.md) — agent guide