> ## Documentation Index
> Fetch the complete documentation index at: https://docs.threetone.in/llms.txt
> Use this file to discover all available pages before exploring further.
# Dynamic variables
> Add named variables to an agent prompt, preserve typed placeholder values in a draft, and review eligible publication.
Dynamic variables let you write reusable text such as `Hello {{customer_name}}.` and store example values alongside the agent configuration. Use fictitious values while preparing a prompt so you can review which information it expects.
This guide covers template and placeholder authoring. Conversation execution is currently gated; a saved placeholder does not demonstrate live substitution or a working client integration. Review [current availability](/agents-platform/overview#current-availability).
## Before you begin
Open an editable agent and select the intended branch. Use a desktop window to access **Vars** in the editor header. Edits remain in the local working copy until saved through an eligible workflow. Voice and custom-model publication are unavailable; preserve their values in a complete server draft.
Decide which values the text needs. For a support-process example, `customer_name` can use `Sample customer` and `support_topic` can use `Delivery questions`. Keep account credentials and real customer records out of example values.
## Add and review placeholders
In **Agent Configuration**, edit the prompt or **First message** and insert a reference using double braces. For example:
```text theme={null}
Hello {{customer_name}}. I can explain our support process for {{support_topic}}.
```
Use the same spelling wherever you mean the same value. A variable reference identifies expected data; it does not fetch an account record or grant access to a tool.
Open **Vars** in the editor header. The **Dynamic variables** panel lists custom variables found in the configuration and marks missing placeholder values.
Choose a type for each placeholder: **String**, **Number**, **Boolean**, **List**, or **Null**. For the example above, choose String and enter `Sample customer` and `Delivery questions`.
Check that each reference uses the intended name and each placeholder has the intended type. The text should remain appropriate for the data it requests; a name or topic value should not be treated as permission to access an account.
Review the prompt and first message together. A variable may also be referenced by other supported configuration fields, so check existing references before renaming it.
Review both the template text and placeholder map, then save a complete server draft on the selected branch. For an eligible managed text-only configuration, select **Publish**, inspect **Review Changes**, and confirm the branch and **Commit message**. Inspect the resulting draft or published version according to the workflow you used.
Reopen the saved version or use [Get agent](/api-reference/agents-platform/get-agent). Confirm the values under `conversation_config.agent.dynamic_variables.dynamic_variable_placeholders` and record the version ID. This completes the configuration check.
## Names and value types
Names must begin with a letter or underscore. After that, use letters, numbers, underscores, or hyphens. The accepted pattern is `[A-Za-z_][A-Za-z0-9_-]*`. For example, `customer_name` is valid; `customer.name` is not a variable name.
| Value type | Example | Authoring note |
| - | - | - |
| String | `"Sample customer"` | Use for short example text. |
| Number | `3` | Preserve a numeric value when the configuration expects one. |
| Boolean | `false` | Store a boolean rather than the string `"false"`. |
| List | `["Delivery", "Returns"]` | Lists can contain supported values, including nested lists. |
| Null | `null` | An explicit value, distinct from a missing map entry. |
The public placeholder input does not accept objects or maps as values. The placeholder map itself pairs variable names with the supported value types above.
## API configuration
The following fragment shows the stored relationship between first-message text and placeholders. It is a conversation-configuration fragment, not a complete agent or server-draft request.
```json theme={null}
{
"agent": {
"first_message": "Hello {{customer_name}}. I can explain our support process for {{support_topic}}.",
"dynamic_variables": {
"dynamic_variable_placeholders": {
"customer_name": "Sample customer",
"support_topic": "Delivery questions"
}
}
}
}
```
Place this structure under `conversation_config` when preparing the corresponding agent change. [Update agent](/api-reference/agents-platform/update-agent) requires an explicit `branch_id` for conversation-configuration updates. If you create a complete server draft, preserve its other fields and follow [versions and drafts](/agents-platform/deploy/versioning).
## Reserved and private values
Names beginning with `system__` are reserved for platform-provided values. You cannot define them as custom placeholders. Their appearance in a schema or editor list does not establish availability in every runtime context.
Names beginning with `secret__` may be referenced only in supported request-header variable slots. They cannot be read from prompts, first messages, or general tool parameters. A prefix is not a substitute for credential storage or access control; use the supported credential configuration for a tool and keep real secrets out of examples.
## Frequently asked questions
The header control is shown on desktop layouts. Widen the window and check that you are editing an agent rather than viewing a historical version. Version previews and restore operations make placeholder values read-only.
A placeholder is saved example data in the agent configuration. Supplying authenticated per-conversation values needs a supported session path and its own verification. This guide does not establish a working runtime integration.
Check that the placeholder map contains the exact referenced name. An explicit `null`, `false`, or `0` is a value; an absent map entry is missing. Also check the name format and reserved prefixes.
A reference does not perform a lookup. Data access requires a separately configured, authorized integration. Review [tools](/agents-platform/configure/tools/overview) before designing a prompt that depends on private records.
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