# MCP deployment (/workflows/deployment/mcp)





Model Context Protocol (MCP) lets an assistant discover and call tools. A Sim workflow MCP server groups deployed workflows into tools an external client can invoke.

You need workspace **Admin** access to create or change workflow MCP servers and add or remove workflow tools. Organization permission groups can also restrict MCP deployment. Read access lets members view servers.

## Create an MCP server [#creating-and-managing-mcp-servers]

1. Open **Settings → MCP Servers** and click **Add**.
2. Enter a name and optional description.
3. Choose **API Key** or **Public** access.
4. Optionally select already-deployed workflows to add immediately.
5. Click **Add Server**, then open **Details** and copy its URL.

Private clients send `X-API-Key` when connecting. For public servers, omit that header.

<Callout type="warn">
  A public server exposes its configured workflow tools without authentication. Review the actions and outputs of every tool on the server before enabling public access.
</Callout>

## Add a workflow as a tool [#adding-a-workflow-as-a-tool]

Deploy the workflow before adding it to a server:

1. Open the workflow's **Deploy → MCP** tab.
2. Enter the tool name and description.
3. Review the parameters derived from the deployed Start inputs.
4. Select the MCP servers that should expose the tool.
5. Click **Save Tool**.
6. Connect a client and confirm that it lists and can call the tool. Check the run in [Logs](/logs-debugging).

Tools execute the workflow's active deployment, like ordinary API calls. Deploy an update after changing workflow logic or inputs.

## Tool configuration [#tool-configuration]

### Tool name [#tool-name]

Use lowercase letters, numbers, and underscores, such as `search_documents`. Choose a name that distinguishes the action from other tools on the server.

### Description [#description]

Describe what the workflow does and when it should be called. A blank description falls back to the workflow's description when available.

### Parameters [#parameters]

The workflow's deployed input fields become tool parameters. Their descriptions default to the descriptions on Start's **Inputs**. Set a per-tool override only when that tool needs different wording; it does not edit Start.

Redeploy to make changes to Start fields and default descriptions available to the tool. Preserve meaningful descriptions so the client knows what values to supply.

## Connect an MCP client [#connecting-mcp-clients]

Open your server's **Details**, copy its URL, and choose a client under **MCP Client**. The UI offers client presets, but check the current client documentation when its configuration differs from a generated example.

The examples below connect directly over HTTP. Replace `YOUR_SERVER_URL`; private servers also require a valid Sim API key. For public servers, remove the authentication header settings.

### Cursor [#cursor]

In `.cursor/mcp.json`, use Cursor's environment interpolation syntax:

```json
{
  "mcpServers": {
    "my-sim-workflows": {
      "url": "YOUR_SERVER_URL",
      "headers": { "X-API-Key": "${env:SIM_API_KEY}" }
    }
  }
}
```

Make `SIM_API_KEY` available to the Cursor process. Cursor also has a one-click install link in Sim's server details. See [Cursor's MCP configuration](https://cursor.com/docs/mcp#config-interpolation).

### Codex [#codex]

In `~/.codex/config.toml`:

```toml
[mcp_servers."my-sim-workflows"]
url = "YOUR_SERVER_URL"
env_http_headers = { "X-API-Key" = "SIM_API_KEY" }
```

Set `SIM_API_KEY` in the environment before starting Codex. `env_http_headers` maps a header name to an environment-variable name; it does not contain the key itself. See [official OpenAI MCP documentation](https://learn.chatgpt.com/docs/extend/mcp?surface=cli).

### Claude Code [#claude-code]

```bash
claude mcp add --transport http my-sim-workflows 'YOUR_SERVER_URL' \
  --header "X-API-Key: $SIM_API_KEY"
```

The shell expands the variable in this command. Follow [Claude Code's MCP instructions](https://code.claude.com/docs/en/mcp#option-1-add-a-remote-http-server) for configuration scope and authentication.

### Claude Desktop [#claude-desktop]

Add a remote custom connector with the server URL. For a private server, add `X-API-Key` and its value under **Request headers**. For a public server, use the no-sign-in configuration without a key.

Remote connectors reach the server from Anthropic's infrastructure, even when used in Claude Desktop. The server must be reachable from that service; a URL reachable only on your computer is insufficient. Team/Enterprise connector administration also has its own Claude-side permissions. See [Claude's current custom-connector setup](https://support.claude.com/en/articles/11175166-get-started-with-custom-connectors-using-remote-mcp).

### VS Code [#vs-code]

Use direct HTTP in `.vscode/mcp.json`. An input prompt keeps the key out of the checked-in configuration:

```json
{
  "inputs": [
    {
      "type": "promptString",
      "id": "sim-api-key",
      "description": "Sim API key",
      "password": true
    }
  ],
  "servers": {
    "my-sim-workflows": {
      "type": "http",
      "url": "YOUR_SERVER_URL",
      "headers": { "X-API-Key": "${input:sim-api-key}" }
    }
  }
}
```

For a public server, remove `headers` and the unused input. See [VS Code's MCP configuration reference](https://code.visualstudio.com/docs/agents/reference/mcp-configuration).

### Sim [#sim]

Choose **Sim** in the server's client picker to use the supported Sim connection flow. [Using MCP tools](/agents/mcp) explains connected server tools in Agent blocks.

## Server management [#server-management]

From **Settings → MCP Servers**, open the server to view its URL and tools, add deployed workflows, or remove tools. Removing a tool removes that exposure; it does not delete the workflow.

Deleting a server removes the server and its configured tools. Disconnect clients that used its URL, or point them at a replacement server.

### Permission requirements [#permission-requirements]

| Action | Required workspace role |
| - | - |
| View workflow MCP servers | Read, Write, or Admin |
| Create, update, or delete workflow MCP servers | Admin |
| Add or remove workflow tools | Admin |

These management operations do not accept workspace API keys. Invoking a private server is a separate authenticated operation with its own key/OAuth access and scope requirements.

## Related docs [#related-docs]

* [Deployment](/workflows/deployment)
* [Start inputs](/workflows/triggers/start)
* [Using MCP tools](/agents/mcp)
* [Workflow MCP server API](/api-reference/mcp-servers/listWorkflowMcpServers)