# apply_design_system

Applies a design system to a list of screens. Use this tool when the user wants to update one or more screens to match the style of a design system. This tool applies the selected design system's foundational design tokens (colors, fonts, shapes, etc.) to the chosen screens, modifying their appearance to align with the design system.

Agent View of the PolicyLayer registry record for `apply_design_system`. HTML page: https://policylayer.com/tools/com-googleapis-stitch-mcp/apply-design-system

## Facts

- Tool: `apply_design_system`
- Server: Mcp (`https://stitch.googleapis.com/mcp`) — https://policylayer.com/tools/com-googleapis-stitch-mcp.md
- Homepage: https://github.com/https://stitch.googleapis.com/mcp
- Risk category: Write (Medium risk)
- Registry record: grade D, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 3 (3 required)
- Recommended policy verdict: Rate-limited

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `assetId` | string | yes | Required. The asset id of the design system to apply, can be fetched from 'list_design_systems'. Example: '15996705518239280238', without the `assets/` prefix. |
| `projectId` | string | yes | Required. The project ID of screen instances to edit, example: '4044680601076201931', without the `projects/` prefix. |
| `selectedScreenInstances` | array | yes | Required. The screen instances to edit, which is available in the Project info, fetched by `get_project`. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "apply_design_system",
    "arguments": {
      "assetId": "<assetId>",
      "projectId": "<projectId>",
      "selectedScreenInstances": []
    }
  }
}
```

## Why apply_design_system is rated Medium

This tool creates or modifies screen designs by applying design tokens (colors, fonts, shapes) to existing screens. The changes are reversible (design systems can be reapplied or changed), making it a Write operation rather than Destructive. The blast radius is medium because it affects visual design assets but does not delete data, execute arbitrary code, or trigger financial transactions.

From the tool's own definition: "Tool description states it 'Applies a design system to a list of screens' and 'modifying their appearance to align with the design system.' The verb 'Applies' combined with 'modifying' indicates creation or modification of screen data."

## Use case

AI agents use apply_design_system to create or update resources in Mcp, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mcp environment.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Mcp:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "apply_design_system": {
      "limits": [
        {
          "counter": "apply_design_system_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Mcp (14)

- `delete_project` — Destructive — https://policylayer.com/tools/com-googleapis-stitch-mcp/delete-project.md
- `get_project` — Read — https://policylayer.com/tools/com-googleapis-stitch-mcp/get-project.md
- `get_screen` — Read — https://policylayer.com/tools/com-googleapis-stitch-mcp/get-screen.md
- `list_design_systems` — Read — https://policylayer.com/tools/com-googleapis-stitch-mcp/list-design-systems.md
- `list_projects` — Read — https://policylayer.com/tools/com-googleapis-stitch-mcp/list-projects.md
- `list_screens` — Read — https://policylayer.com/tools/com-googleapis-stitch-mcp/list-screens.md
- `create_design_system` — Write — https://policylayer.com/tools/com-googleapis-stitch-mcp/create-design-system.md
- `create_design_system_from_design_md` — Write — https://policylayer.com/tools/com-googleapis-stitch-mcp/create-design-system-from-design-md.md
- `create_project` — Write — https://policylayer.com/tools/com-googleapis-stitch-mcp/create-project.md
- `edit_screens` — Write — https://policylayer.com/tools/com-googleapis-stitch-mcp/edit-screens.md
- `generate_screen_from_text` — Write — https://policylayer.com/tools/com-googleapis-stitch-mcp/generate-screen-from-text.md
- `generate_variants` — Write — https://policylayer.com/tools/com-googleapis-stitch-mcp/generate-variants.md
- `update_design_system` — Write — https://policylayer.com/tools/com-googleapis-stitch-mcp/update-design-system.md
- `upload_design_md` — Write — https://policylayer.com/tools/com-googleapis-stitch-mcp/upload-design-md.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=com-googleapis-stitch-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/com-googleapis-stitch-mcp