# Custom templates (/docs/mcp/custom-templates)

<!-- agent-signals: reading_time_min: 2 · est_tokens: 1107 · updated: 2026-07-30 -->
Related: [Available servers](/docs/mcp/available-servers.md), [Custom servers](/docs/mcp/custom-servers.md), [Examples](/docs/mcp/examples.md), [Quickstart](/docs/mcp/quickstart.md)

You can prepull MCP server Docker images during template build time to significantly improve runtime performance.

## How it works [#how-it-works]

When you build a template with prepulled MCP servers, the Docker images for those servers are downloaded and cached during the build process. This means when you create a sandbox from that template, the MCP servers are ready to use immediately without waiting for image downloads.

<Info>
  You must use the MCP gateway enabled template (`mcp-gateway`) as your base template to use this feature.
</Info>

## Building a template with MCP servers [#building-a-template-with-mcp-servers]

Use the `addMcpServer()` method (TypeScript) or `add_mcp_server()` method (Python) to prepull MCP server images during template build. You can pass a single server or an array of servers.

The server names (like `"browserbase"` and `"exa"`) correspond to the keys defined in the [Available Servers](/docs/mcp/available-servers) documentation.

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    <CodeBlockTab value="JavaScript & TypeScript">
      ```typescript  
      import "dotenv/config";
      import { Template, defaultBuildLogger } from 'e2b';

      export const template = Template()
        .fromTemplate("mcp-gateway")
        .addMcpServer(["browserbase", "exa"]);

      await Template.build(template, 'my-mcp-gateway', {
        cpuCount: 8,
        memoryMB: 8192,
        onBuildLogs: defaultBuildLogger(),
      });
      ```
    </CodeBlockTab>

    <CodeBlockTab value="Python">
      ```python  
      from dotenv import load_dotenv
      from e2b import Template, default_build_logger

      load_dotenv()

      template = (
          Template()
          .from_template("mcp-gateway")
          .add_mcp_server(["browserbase", "exa"])
      )

      Template.build(
          template,
          'my-mcp-gateway',
          cpu_count=8,
          memory_mb=8192,
          on_build_logs=default_build_logger(),
      )
      ```
    </CodeBlockTab>
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## Using the template [#using-the-template]

Once built, create sandboxes from your template. You still need to provide the configuration for each MCP server.

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    <CodeBlockTab value="JavaScript & TypeScript">
      ```typescript  
      import { Sandbox } from 'e2b';

      const sandbox = await Sandbox.create({
          template: "my-mcp-gateway",
          mcp: {
              browserbase: {
                  apiKey: process.env.BROWSERBASE_API_KEY!,
                  geminiApiKey: process.env.GEMINI_API_KEY!,
                  projectId: process.env.BROWSERBASE_PROJECT_ID!,
              },
              exa: {
                  apiKey: process.env.EXA_API_KEY!,
              },
          },
      });

      ```
    </CodeBlockTab>

    <CodeBlockTab value="Python">
      ```python  
      from e2b import Sandbox
      import os

      sbx = Sandbox.create(
          template="my-mcp-gateway",
          mcp={
              "browserbase": {
                  "apiKey": os.getenv("BROWSERBASE_API_KEY"),
                  "geminiApiKey": os.getenv("GEMINI_API_KEY"),
                  "projectId": os.getenv("BROWSERBASE_PROJECT_ID"),
              },
              "exa": {
                  "apiKey": os.getenv("EXA_API_KEY"),
              },
          }
      )
      ```
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## Learn more [#learn-more]

For more information about working with templates, see:

* [Template Quickstart](/docs/template/quickstart) - Get started with custom templates
* [Defining Templates](/docs/template/defining-template) - Learn all template configuration options
* [Template Build](/docs/template/build) - Understand the build process