---
title: 'A config-driven agent'
description: 'A hotel concierge that reads its tone from config at runtime, so an operator can change how it speaks without a redeploy.'
position: 2
---

# A config-driven agent

> This concierge reads its tone from [config](/docs/sdk/platform/config)
> instead of hard-coding it in the prompt. A tool exposes the current setting
> and the prompt tells the model to adopt it. Config reads come back as
> a `{ data, error }` envelope, so the tool picks its own fallback when the key
> is not set.

The agent is a single `deep-agents/concierge/index.ts` file, the same shape as
[the greeter](/docs/examples/agents/plain-greeter). The difference is the tool:
it reads the `tone` key from the ambient `stackbone` client every time the model
asks for it.

```ts
// deep-agents/concierge/index.ts
import { tool } from '@langchain/core/tools';
import { z } from 'zod';
import { defineDeepAgent } from '@stackbone/sdk/deep';
import { stackbone } from '@stackbone/sdk';

const getTone = tool(
  async () => {
    const tone = await stackbone.config.get('tone');
    return tone.error ? 'neutral' : String(tone.data);
  },
  {
    name: 'get_tone',
    description: "Return the agent's current tone setting.",
    schema: z.object({}),
  },
);

export default defineDeepAgent({
  name: 'concierge',
  model: 'openai/gpt-4o-mini',
  tools: [getTone],
});
```

The prompt keyed `concierge` is what tells it to use the tool:

```text
You are a hotel concierge.
Before your first reply in a conversation, call get_tone and adopt that tone
(for example "formal" or "playful") for the rest of the chat.
```

Because the tone comes from config, the operator sets it once and every new
conversation picks it up.

The operator sets the tone once in config, and the agent reads it at the start
of each new conversation. They edit the value in the dashboard, or you push one
from the CLI with `stackbone config set`. See
[Setting config](/docs/sdk/platform/config#setting-config).

The read above is untyped: `tone.data` arrives as `unknown`, so the tool wraps
it in `String(...)`. Declare a `config.schema.ts` at your project root and
run `stackbone config types` to make it strict. `stackbone.config.get('tone')`
then returns `string`, and a misspelt key is a compile error. See
[Typed config](/docs/sdk/platform/config#typed-config).

## What's next

- **[A plain greeter](/docs/examples/agents/plain-greeter)**: the same agent
  with the tone written straight into its prompt.
- **[A retrieval-backed support agent](/docs/examples/agents/retrieval-backed)**:
  two tools, one over a knowledge base and one over a database.
- **[What is an agent](/docs/sdk/agents/overview)**: the model behind this
  example.
- **[SDK overview](/docs/sdk/reference/overview)**: every surface a tool can
  reach (`config`, `storage`, `rag`, `database`, `ai`, and more).