# controller_tick

`station__cybercinetics__controller_tick` · external (needs EXECUTION_BACKEND_URL configured) · domain `cybercinetics` · pv-relevance `non-pv`

Run one tick of the feedback controller. Evaluates frequency decay (ν), causal chain fidelity (→), and recursion saturation (ρ) to produce a verdict: STABLE, FREQ_DECAY, FIDELITY_DEGRADED, RECURSION_SATURATED, or COMPOUND.

> **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

- `nu_rate` *number* (required) — Current measured frequency (Hz or iterations/sec)
- `nu_floor` *number* (required) — Minimum acceptable frequency before decay verdict
- `rho_ceiling` *integer* — Maximum recursion depth (default: 3)
- `f_min` *number* — Minimum fidelity threshold for causal chain (default: 0.80)
- `rho_depth` *integer* — Current recursion depth (default: 0)
- `causal_links` *array* — Array of {cause, effect, fidelity} objects forming the causal chain

## Example call

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

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "station__cybercinetics__controller_tick",
    "arguments": {
      "nu_rate": 0,
      "nu_floor": 0
    }
  }
}
```

## Related

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