---
title: "tool si.work.lay_strategy"
description: "Lays one strategy on one twin, with the bounds of the run: The call returns the simulation whose interventions are the strategy's armed plays, then the frame."
section: reference
address: /reference/tools/si-work-lay_strategy
contract: 0476e35e6e275db5
---

# tool si.work.lay_strategy

Lays one strategy on one twin, with the bounds of the run: The call returns the simulation whose interventions are the strategy's armed plays, then the frame.

[figure: Over MCP, si.work.lay_strategy takes LayStrategyInput and returns a card whose body is MarketSimulation.]

The call returns the simulation whose interventions are the strategy's armed plays, then the frame. The call needs the work grant at the strategy rung.



| | |
|---|---|
| input | [LayStrategyInput](/concepts/laystrategyinput) |
| result | a card whose body is [MarketSimulation](/concepts/marketsimulation) |
| read-only | no |
| destructive | no |
| card address | `ui://scale-intelligence/cards/MarketSimulation` |
| HTTP route | [`/v1/work/lay_strategy`](/reference/work/lay_strategy) |





| field | type | required | note |
|---|---|---|---|
| `twin` | `id` | yes |  |
| `strategy` | `id` | yes |  |
| `horizon` | `duration` | no |  |
| `samples` | `count` | no |  |
| `seed` | `count` | no |  |