# Flag

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

> Feature flags: ship it dark, then turn it on for who you pick.

Also for this capability: **API** · [CLI](https://docs.hanzo.ai/docs/cli/flag) · [MCP](https://docs.hanzo.ai/docs/mcp-tools/flag) · [SDKs](https://docs.hanzo.ai/docs/sdks)

Feature flags: ship it dark, then turn it on for who you pick.

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

|                |                                        |
| -------------- | -------------------------------------- |
| **Base URL**   | `https://api.hanzo.ai`                 |
| **Operations** | 8                                      |
| **Auth**       | `Authorization: Bearer $HANZO_API_KEY` |

## Specification

Specification pending — no HIP in [hanzoai/hips](https://github.com/hanzoai/hips) declares `capability: flag` yet. What this capability serves is below, from the API document; what it is — the store it owns, how it meters, what it publishes — is written as a HIP under HIP-0139.

## Four surfaces

| Surface  | Reaches this capability as                   | Coverage                                                                  |
| -------- | -------------------------------------------- | ------------------------------------------------------------------------- |
| **REST** | `flag` at its own prefix                     | 8 operations                                                              |
| **CLI**  | `hanzo flag …`                               | 8 of 8                                                                    |
| **SDK**  | `FlagApi` in every published client          | 8 methods                                                                 |
| **MCP**  | tool `flag` on `https://api.hanzo.ai/v1/mcp` | 8 operations, 2 under the document's own id — ask `describe` for the rest |

## Quickstart

```bash
export HANZO_API_KEY=sk-...   # console.hanzo.ai → API keys
```

Then the first call — a read that needs nothing but the key. `GET /v1/flag/defs`, operation `get_flag_defs`:

**CLI**

```bash
hanzo flag defs list
```

**SDK**

**.ts**

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

const api = new FlagApi(new Configuration({ accessToken: process.env.HANZO_API_KEY }));
const { data } = await api.getFlagDefs();
```

**.py**

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

client = ApiClient(Configuration(access_token=os.environ["HANZO_API_KEY"]))
result = FlagApi(client).get_flag_defs()
```

**.go**

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

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

**.rs**

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

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

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

**.java**

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

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

var result = new FlagApi(client).getFlagDefs();
```

**HTTP**

```bash
curl https://api.hanzo.ai/v1/flag/defs \
  -H "Authorization: Bearer $HANZO_API_KEY"
```

**MCP**

MCP reaches **flag** through the `flag` tool, which names its 8 operations with its own verbs — this one among them, under a name only MCP declares. `describe` explains any of them:

```bash
curl -X POST https://api.hanzo.ai/v1/mcp \
  -H "Content-Type: application/json" \
  -d '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "tools/call",
       "params": {
         "name": "describe",
         "arguments": {
           "op": "get_flag_activity"
         }
       }
     }'
```

Answers `200` with `object` — ok.

## Endpoints

| Endpoint                                                                                        | What it does                                                                                                                                                                           |
| ----------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [`GET /v1/flag/activity`](https://docs.hanzo.ai/docs/openapi/flag/get-flag-activity)            | Returns the caller's flag change log newest-first: every create, update and delete, with the actor and the time.                                                                       |
| [`POST /v1/flag/decide`](https://docs.hanzo.ai/docs/openapi/flag/post-flag-decide)              | Runs the caller's flag definitions for one identity and returns the flag verdict: which flags are on (or which variant), their payloads, and whether any definition failed to compute. |
| [`GET /v1/flag/defs/{key}`](https://docs.hanzo.ai/docs/openapi/flag/get-flag-defs-by-key)       | Returns one flag definition by key, or 404 when the caller's store has none under that key.                                                                                            |
| [`PUT /v1/flag/defs/{key}`](https://docs.hanzo.ai/docs/openapi/flag/put-flag-defs-by-key)       | Creates or replaces the flag definition at the path's key and returns the stored row.                                                                                                  |
| [`DELETE /v1/flag/defs/{key}`](https://docs.hanzo.ai/docs/openapi/flag/delete-flag-defs-by-key) | Removes one flag definition by key and records the deletion in the change log.                                                                                                         |
| [`GET /v1/flag/defs`](https://docs.hanzo.ai/docs/openapi/flag/get-flag-defs)                    | Returns every flag definition in the caller's (org, project) store, by key, with its version and who last changed it.                                                                  |
| [`GET /v1/flag/health`](https://docs.hanzo.ai/docs/openapi/flag/get-flag-health)                | Reports that the flag engine is serving.                                                                                                                                               |
| [`POST /v1/flag`](https://docs.hanzo.ai/docs/openapi/flag/post-flag)                            | Runs the caller's flag definitions for one identity and returns the flag verdict: which flags are on (or which variant), their payloads, and whether any definition failed to compute. |

---

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