# Create chat — POST /v1/ai/mcp/chat

URL: https://docs.hanzo.ai/docs/openapi/ai/aichat

> Asks one model one prompt and answers the reply, which model served it and who paid.

`POST /v1/ai/mcp/chat`

> [AI →](https://docs.hanzo.ai/docs/openapi/ai) · [All API references →](https://docs.hanzo.ai/docs/openapi) · [Get started →](https://docs.hanzo.ai/docs/guides)

|               |                                        |
| ------------- | -------------------------------------- |
| **Address**   | `https://api.hanzo.ai/v1/ai/mcp/chat`  |
| **Method**    | `POST`                                 |
| **Operation** | `aiChat`                               |
| **Auth**      | `Authorization: Bearer $HANZO_API_KEY` |

Asks one model one prompt and answers the reply, which model served it and who
paid. The call is the caller's own POST /v1/chat/completions, run as the caller,
so it is gated, billed and refused exactly as that route is; a refusal names its
code and what lifts it, never an amount. An empty model asks the deployment's
default Hanzo model.

## Request

4 fields, body `application/json` (required).

| Field        | In   | Type            | Required | Description                                                                                               |
| ------------ | ---- | --------------- | -------- | --------------------------------------------------------------------------------------------------------- |
| `max_tokens` | body | integer (int64) | —        | MaxTokens bounds the answer in tokens; 0 leaves it to the model.                                          |
| `model`      | body | string          | —        | Model is the model to answer, by id (zen5, enso, kai, anthropic/claude-sonnet-4.5 — aiModels lists them). |
| `prompt`     | body | string          | —        | Prompt is what to ask.                                                                                    |
| `system`     | body | string          | —        | System is the system message ahead of the prompt, when set.                                               |

## Response

| Status    | Body            | Meaning |
| --------- | --------------- | ------- |
| `200`     | aiChat          | ok      |
| `default` | problem-details | refused |

`200` body — 10 fields.

| Field              | In   | Type      | Always | Description                                                                                                       |
| ------------------ | ---- | --------- | ------ | ----------------------------------------------------------------------------------------------------------------- |
| `answer`           | body | string    | —      | Answer is the model's reply.                                                                                      |
| `model`            | body | string    | —      | Model is the model asked: the caller's, or the default when it named none.                                        |
| `receipt`          | body | aiReceipt | —      |                                                                                                                   |
| `receipt.class`    | body | string    | —      | Class is the model's class as billed: premium, ours or free (X-Hanzo-Usage-Class).                                |
| `receipt.fallback` | body | string    | —      | Fallback is the model that answered in place of the one asked, in limited mode (X-Hanzo-Fallback).                |
| `receipt.paid_by`  | body | string    | —      | PaidBy is plan, credits or free (X-Hanzo-Paid-By); absent when the answer named no payer, as a free model's does. |
| `receipt.reason`   | body | string    | —      | Reason is the refusal code that sent the request to the fallback (X-Hanzo-Usage-Reason).                          |
| `receipt.routed`   | body | string    | —      | Routed is the model `auto` resolved to (X-Routed-Model).                                                          |
| `receipt.served`   | body | string    | —      | Served is the model that answered (X-Hanzo-Served).                                                               |
| `receipt.usage`    | body | string    | —      | Usage is where that class stands for the payer: ok, near or limited (X-Hanzo-Usage).                              |

Failure carries the platform error shape — see [Errors](https://docs.hanzo.ai/docs/errors).

## Examples

**CLI**

`hanzo` has no subcommand for this operation — the CLI serves only what cloud's live route table confirms. Use HTTP or an SDK.

**SDK**

**.ts**

```ts
import { Configuration, AiApi } from 'hanzoai';

const api = new AiApi(new Configuration({ accessToken: process.env.HANZO_API_KEY }));
const { data } = await api.aiChat({ max_tokens: 0, model: "<model>" });
```

**.py**

```python
from hanzoai.cloud import ApiClient, Configuration
from hanzoai.cloud.api import AiApi

client = ApiClient(Configuration(access_token=os.environ["HANZO_API_KEY"]))
result = AiApi(client).ai_chat(max_tokens=0, model="<model>")
```

**.go**

```go
cfg := hanzoai.NewConfiguration()
cfg.AddDefaultHeader("Authorization", "Bearer "+os.Getenv("HANZO_API_KEY"))
client := hanzoai.NewAPIClient(cfg)

resp, _, err := client.AiAPI.AiChat(context.Background()).Execute()
if err != nil {
	return err
}
```

**.rs**

```rust
use hanzo_client::apis::{configuration::Configuration, ai_api};

let mut cfg = Configuration::new();
cfg.bearer_access_token = std::env::var("HANZO_API_KEY").ok();

let result = ai_api::ai_chat(&cfg, Default::default()).await?;
```

**.java**

```java
import ai.hanzo.cloud.ApiClient;
import ai.hanzo.cloud.api.AiApi;

ApiClient client = new ApiClient();
client.setBearerToken(System.getenv("HANZO_API_KEY"));

var result = new AiApi(client).aiChat();
```

**HTTP**

```bash
curl -X POST https://api.hanzo.ai/v1/ai/mcp/chat \
  -H "Authorization: Bearer $HANZO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
       "max_tokens": 0,
       "model": "<model>"
     }'
```

**MCP**

MCP declares no tool for **ai** — `tools/list` on `https://api.hanzo.ai/v1/mcp` names the products it does reach. Use HTTP or an SDK.

---

[AI API](https://docs.hanzo.ai/docs/openapi/ai) · [All Hanzo APIs](https://docs.hanzo.ai/docs/openapi) · [Interactive reference](https://docs.hanzo.ai/docs/openapi/reference)