# Configuring environments

## Reading environment variables

You can read environment variables directly from `process.env` in your Gram Functions. Preconfigured values defined in `envSchema` can also be accessed from `ctx.env` in the Functions Framework:

```typescript

const gram = new Gram({
  envSchema: {
    SCHEMA_VALUE: z.string(),
  },
}).tool({
  name: "fetch_data",
  description: "Fetch data from an external API",
  inputSchema: { endpoint: z.string() },
  async execute(ctx, input) {
    const arbitraryValue = process.env.ARBITRARY_VALUE;
    const schemaValue = ctx.env.SCHEMA_VALUE;
    const response = await fetch(`${arbitraryValue}/${input.endpoint}`);
    return ctx.json(await response.json());
  },
});

```

## Declaring environment variables with envSchema

You can set up environment variables that end users will provide using `envSchema`. Environment variables specified in the `envSchema` can be provided by MCP users via headers or via Gram environments.

### Using the Functions Framework

Declare environment variables using `envSchema` in the Functions Framework:

```typescript

const gram = new Gram({
  envSchema: {
    API_KEY: z.string(),
    BASE_URL: z.string().url(),
  },
}).tool({
  name: "api_call",
  inputSchema: { endpoint: z.string() },
  async execute(ctx, input) {
    const baseUrl = ctx.env.BASE_URL;
    const apiKey = ctx.env.API_KEY;
    const response = await fetch(`${baseUrl}/${input.endpoint}`, {
      headers: { Authorization: `Bearer ${apiKey}` },
    });
    return ctx.json(await response.json());
  },
});

```

### Using the MCP SDK

Declare environment variables using the `variables` option with the MCP SDK wrapper:

```typescript

```

## Attaching environments to Functions in Gram

To attach an environment to your Gram Function, first ensure you have [created an environment](/docs/mcp/build/toolsets/configuring-environments) with the configuration values you want to attach.

Then follow these steps:

- Navigate to the **Toolsets** tab.
- Click the **More Actions** (<MoreVertical className="inline" size={16} />) menu on the Source Card for your Gram Function.

  ![More Actions menu on Source Card](/assets/docs/gram/img/build-mcp/attach-env-more-actions-menu.png)

- Click **Attach Environment**.

  ![Attach Environment menu option](/assets/docs/gram/img/build-mcp/attach-env-select-dialog.png)

- Select the environment you created in the first step.

These environment values will now apply to all users of the Function.

<Callout title="Warning" type="warning">
A configuration attached to a Function source will apply to all users, including users of public MCP servers. Be careful not to include user-specific credentials or tokens that should only be available to certain users.
</Callout>

## Providing environment configuration from clients

If you have a Gram API key, you can provide that key and a `GRAM_ENVIRONMENT` header set to the slug for your environment. For an example of using environments with the Gram SDKs, see [the guide to using environments with the Vercel AI SDK](/docs/mcp/build/examples/using-environments-with-vercel-ai-sdk).

You can also configure your MCP client to send headers with environment configurations. For more information, check the documentation for installing your MCP server on the client of your choosing.