# reactive

`station__preemptive-pv__reactive` · external (needs EXECUTION_BACKEND_URL configured) · domain `preemptive-pv` · pv-relevance `pv-core`

Tier 1: Standard reactive signal detection from a 2x2 contingency table. Returns PRR, chi-squared, and detection verdict.

> **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

- `a` *integer* (required) — Drug+Event+ count
- `b` *integer* (required) — Drug+Event- count
- `c` *integer* (required) — Drug-Event+ count
- `d` *integer* (required) — Drug-Event- count

## Example call

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

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "station__preemptive-pv__reactive",
    "arguments": {
      "a": 0,
      "b": 0,
      "c": 0,
      "d": 0
    }
  }
}
```

## Related

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