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

# Invoke a backend

> Call a deployed AXTL backend from your application.

# Invoke a backend

After deployment, invoke the backend through its AXTL agent slug with an agent API key.

Agent API keys are different from platform bearer tokens. Create one before calling a deployed backend:

```bash theme={null}
curl -X POST "$AXTL_API_BASE_URL/v1/agents/{agentId}/api-keys" \
  -H "Authorization: Bearer $AXTL_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"name":"Production"}'
```

Copy the returned `data.key`.

## Invoke by slug

```bash theme={null}
curl -X POST "$AXTL_API_BASE_URL/v1/invoke/{agentSlug}" \
  -H "Authorization: Bearer $AXTL_AGENT_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "input": "Classify this support request and suggest a next action."
  }'
```

AXTL forwards the JSON request body to the generated backend runtime. The generated backend decides the final request and response schema.

Successful calls return an invocation envelope:

```json theme={null}
{
  "data": {
    "status": 200,
    "ok": true,
    "latencyMs": 123,
    "response": {
      "answer": "ok"
    }
  }
}
```

## Common invocation errors

| Error                          | Meaning                                              |
| ------------------------------ | ---------------------------------------------------- |
| `missing_agent_api_key`        | The request did not include an agent API key.        |
| `malformed_agent_api_key`      | The authorization header was not a bearer agent key. |
| `invalid_agent_api_key`        | The agent API key was not recognized.                |
| `agent_api_key_revoked`        | The agent API key was revoked.                       |
| `agent_api_key_scope_mismatch` | The key belongs to a different agent.                |
| `not_deployed`                 | The agent does not have a live endpoint yet.         |
| `invalid_json`                 | The request body was not valid JSON.                 |
| `endpoint_timeout`             | The deployed backend timed out.                      |
| `endpoint_unreachable`         | AXTL could not reach the deployed backend.           |