> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bigdata.com/llms.txt
> Use this file to discover all available pages before exploring further.

# bigdata_simulate_monitor

> Preview a search monitor on a recent window, or replay its scheduled runs over a past period.

## Overview

The `bigdata_simulate_monitor` tool runs a search monitor without activating it. It has two modes:

* **Flash** (default): previews one recent window. No dates, no novelty check, and no email
* **Full**: replays the monitor's scheduled runs over a past period

The tool starts the simulation and returns a `simulation_id` straight away. Read the results with [`bigdata_get_monitor_runs`](https://docs.bigdata.com/mcp-reference/tools/bigdata-get-monitor-runs).

## When to Use

Simulate Monitor is ideal for:

* **Checking a new monitor:** Running a flash preview after [`bigdata_create_monitor`](https://docs.bigdata.com/mcp-reference/tools/bigdata-create-monitor) and before activating
* **Checking an edit:** Previewing the effect of new queries, entities, or schema
* **Backtesting:** Replaying the schedule over a past period to see what the monitor would have caught

## How It Works

1. **Call** `bigdata_simulate_monitor` with the monitor `id`, and a `mode` and dates for a full simulation
2. **Keep** the returned `simulation_id` and `mode`
3. **Read** the results with [`bigdata_get_monitor_runs`](https://docs.bigdata.com/mcp-reference/tools/bigdata-get-monitor-runs), passing the same `simulation_id` and `mode`

## Parameters

| Parameter | Type | Required | Description |
| - | - | - | - |
| `id` | string | Yes | ID of the monitor to simulate. |
| `mode` | string | No | `flash` (default) or `full`. |
| `end_timestamp` | string | For `full` | End of the period, ISO 8601 UTC. Must be at least 5 minutes in the past. |
| `start_timestamp` | string | No | Start of the period, ISO 8601 UTC. `full` only. Without it, the simulation covers the single run ending at `end_timestamp`. |

**Flash**

```json theme={null}
{"id": "b0253b18-0dd8-4a01-a9a4-f209bce91a26"}
```

**Full**

```json theme={null}
{
  "id": "b0253b18-0dd8-4a01-a9a4-f209bce91a26",
  "mode": "full",
  "start_timestamp": "2026-11-01T00:00:00Z",
  "end_timestamp": "2026-11-04T00:00:00Z"
}
```

### Important Notes

* Flash does not accept dates. Sending `start_timestamp` or `end_timestamp` with flash returns an error
* Full requires `end_timestamp`
* A full simulation can cover at most 90 runs. The API's rejection of the period is returned as the error
* A full simulation emails its result if the monitor already has email delivery set. Flash never sends email
* An unknown monitor `id` returns a not-found error

## Data Returned

| Field | Description |
| - | - |
| `simulation_id` | Simulation ID. Pass it to `bigdata_get_monitor_runs` |
| `mode` | `flash` or `full`. Pass it to `bigdata_get_monitor_runs` |
| `status` | Status when the simulation was accepted. A flash simulation always returns `PENDING` |
| `retention_warning` | Full only. Set when part of the period is older than the news the monitor can still read. Otherwise `null` |
| `runs_requested` | Full only. Number of scheduled runs in the period |

```json theme={null}
{
  "simulation_id": "019a6a4e-8f3c-7b21-9d4e-2f1a6c0b5e77",
  "mode": "full",
  "status": "PENDING",
  "retention_warning": null,
  "runs_requested": 12
}
```

## Practical Tips

### Start with flash

Run a flash preview first. It is quick and does not send email. Use full only when the user wants to see past results over a specific period.

### Watch the retention warning

If `retention_warning` is set, tell the user that the earliest runs of the period may be missing results because that news is no longer available to the monitor.


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