> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bland.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Set Agent Variable

> Set an environment variable on an agent.

### Overview

Creates or replaces one variable in one of the agent's environments. Reference it from the agent's configuration as `{{env.KEY}}`; the value is substituted when a call runs as that environment. Writes to `production` apply to the next inbound call. See [List Agent Variables](/api-v2/get/agents-id-environments-env-variables) for which environment resolves for each kind of call.

Requires an admin, owner, operator, or prompter role.

### Headers

<ParamField header="authorization" type="string" required>
  Your API key for authentication.
</ParamField>

### Path Parameters

<ParamField path="agent_id" type="string" required>
  The agent's unique identifier.
</ParamField>

<ParamField path="env" type="string" required>
  One of `dev`, `staging`, `production`. Any other value returns `400 INVALID_ENV`.
</ParamField>

<ParamField path="key" type="string" required>
  The variable key. Letters, numbers, and underscores only (`A-Z`, `a-z`, `0-9`, `_`); anything else, including dots and dashes, returns `400 INVALID_KEY`. Surrounding whitespace is trimmed. Keys are case-sensitive as stored, so `Api_Host` and `api_host` are separate variables.
</ParamField>

### Body Parameters

<ParamField body="value" type="any" required>
  The value to store. Any JSON value is accepted, including objects, arrays, and `null`; the field itself must be present or the request returns `400 MISSING_VALUE`. A string that is exactly `{{SECRET.NAME}}` references an existing secret in your organization's secret store and is expanded at call time, for example `{{SECRET.CRM_API_KEY}}`.
</ParamField>

<ParamField body="is_secret" type="boolean" default="false">
  When `true`, `value` is converted to a string, stored in your organization's secret store under a name derived from the agent, environment, and key, and the variable holds only the resulting `{{SECRET.NAME}}` reference. Reads return that reference, never the raw value. Saving the same key again with `is_secret: true` rotates the stored secret; saving it with `is_secret: false` removes the stored secret and keeps the plain value.
</ParamField>

### Response

<ResponseField name="data.variable_key" type="string">
  The key that was written, as trimmed.
</ResponseField>

<ResponseField name="errors" type="null | array">
  `null` on success, or a list of error objects if the request failed.
</ResponseField>

<ResponseExample>
  ```json Response theme={null}
  {
    "data": {
      "variable_key": "CRM_BASE_URL"
    },
    "errors": null
  }
  ```

  ```json Invalid Key theme={null}
  {
    "data": null,
    "errors": [
      {
        "error": "INVALID_KEY",
        "message": "variable key may only contain letters, numbers, and underscores"
      }
    ]
  }
  ```

  ```json Missing Value theme={null}
  {
    "data": null,
    "errors": [
      {
        "error": "MISSING_VALUE",
        "message": "value is required"
      }
    ]
  }
  ```

  ```json Invalid Env theme={null}
  {
    "data": null,
    "errors": [
      {
        "error": "INVALID_ENV",
        "message": "env must be one of: dev, staging, production"
      }
    ]
  }
  ```

  ```json Not Found theme={null}
  {
    "data": null,
    "errors": [
      {
        "error": "NOT_FOUND",
        "message": "Agent not found"
      }
    ]
  }
  ```
</ResponseExample>

***

Docs for agents: [llms.txt](/llms.txt)