---
title: "tool si.act.arm_play"
description: "a strategy, the play and its version, the goal it serves, and the share it is armed on with its holdout (a share under one makes the play an experiment): the armed play with its class proposed from the kind's usual class and the rivals' coverage, and the demand cells it raised."
section: reference
address: /reference/tools/si-act-arm_play
contract: 0476e35e6e275db5
---

# tool si.act.arm_play

a strategy, the play and its version, the goal it serves, and the share it is armed on with its holdout (a share under one makes the play an experiment): the armed play with its class proposed from the kind's usual class and the rivals' coverage, and the demand cells it raised.

[figure: Over MCP, si.act.arm_play takes ArmPlayInput and returns a card whose body is ArmPlayAnswer.]

the armed play with its class proposed from the kind's usual class and the rivals' coverage, and the demand cells it raised. The call needs the act grant at the strategy rung.



| | |
|---|---|
| input | [ArmPlayInput](/concepts/armplayinput) |
| result | a card whose body is [ArmPlayAnswer](/concepts/armplayanswer) |
| read-only | no |
| destructive | yes |
| card address | `ui://scale-intelligence/cards/ArmPlayAnswer` |
| HTTP route | [`/v1/act/arm_play`](/reference/act/arm_play) |





| field | type | required | note |
|---|---|---|---|
| `play` | `id` | yes |  |
| `strategy` | `id` | yes |  |
| `brand` | `id` | yes |  |
| `arm` | `bool` | yes |  |
| `share` | `share` | no | the share of the admitted members the arming admits; absent keeps the play's own |
| `holdout` | `share` | no | the share left alone at random, read as the effect's comparison; absent keeps the play's own |