# play.start

> Talos next · Since next

Play the open scene in the editor; waits until it runs.

It runs the newest READY BUILD: a file you just wrote is applied and built first (several files wait for build.apply; settled says which). A build with unchecked TypeScript is refused. Agents sharing the editor play one at a time: busy is your place in line; a 5-minute lease passes Play on. A sub-agent that passes `agent` plays in its own editor.

| | |
|---|---|
| Title | Play |
| Mode | `editor` |
| Token cost | about 223 tokens (in the default list, paid on every call) |
| Toolset | core |

## Arguments

| Argument | Type | Required | Default | Allowed values | Description |
|---|---|---|---|---|---|
| `agent` | `string` | no |  |  | The name of the agent making the call, when several agents share one connection: each named agent is its own actor and plays its own game. Leave it out when there is one agent. |
| `saveFirst` | `boolean` | no | `true` |  | Save unsaved edits first (default) so their checked build plays. false plays the unsaved scene in memory, unverified, writing nothing |
| `scene` | `string` | no |  |  | A named agent's scene, in its own editor; absent: its open scene, else the editor's |

## Example

An MCP `tools/call` with the required arguments (placeholders in angle brackets).

```json
{
  "name": "play.start",
  "arguments": {}
}
```