Experiment

A/B testing anything: a flag, an ad, a subject line, a model.

Also for this capability: API · CLI · MCP · SDKs

A/B testing anything: a flag, an ad, a subject line, a model.

Base URL	`https://api.hanzo.ai`
Operations	7
Auth	`Authorization: Bearer $HANZO_API_KEY`

Specification

Specification pending — no HIP in hanzoai/hips declares capability: experiment 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	`experiment` at its own prefix	7 operations
CLI	`hanzo experiment …`	7 of 7
SDK	`ExperimentApi` in every published client	7 methods
MCP	tool `experiment` on `https://api.hanzo.ai/v1/mcp`	7 operations, 2 under the document's own id — ask `describe` for the rest

Quickstart

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

Then the first call — a read that needs nothing but the key. GET /v1/experiment, operation get_experiment:

CLI

SDK

HTTP

MCP

hanzo experiment list

.ts

.py

.go

.rs

.java

import { Configuration, ExperimentApi } from 'hanzoai';

const api = new ExperimentApi(new Configuration({ accessToken: process.env.HANZO_API_KEY }));
const { data } = await api.getExperiment();

from hanzoai.cloud import ApiClient, Configuration
from hanzoai.cloud.api import ExperimentApi

client = ApiClient(Configuration(access_token=os.environ["HANZO_API_KEY"]))
result = ExperimentApi(client).get_experiment()

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

resp, _, err := client.ExperimentAPI.GetExperiment(context.Background()).Execute()
if err != nil {
	return err
}

use hanzo_client::apis::{configuration::Configuration, experiment_api};

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

let result = experiment_api::get_experiment(&cfg, Default::default()).await?;

import ai.hanzo.cloud.ApiClient;
import ai.hanzo.cloud.api.ExperimentApi;

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

var result = new ExperimentApi(client).getExperiment();

curl https://api.hanzo.ai/v1/experiment \
  -H "Authorization: Bearer $HANZO_API_KEY"

MCP reaches experiment through the experiment tool, which names its 7 operations with its own verbs — this one among them, under a name only MCP declares. describe explains any of them:

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": "list_experiments"
         }
       }
     }'

Answers 200 with object — ok.

Endpoints

Endpoint	What it does
`POST /v1/experiment/{id}/analyze`	Per-variant conversion, lift and statistical significance against the control arm.
`GET /v1/experiment/{id}/assign`	The variant one subject is bucketed into, and the payload that variant carries.
`POST /v1/experiment/{id}/decide`	Promotes one variant to the whole rollout and records who decided.
`GET /v1/experiment/{id}`	One experiment's definition and lifecycle: variants, weights, control arm, status and winner.
`GET /v1/experiment/health`	Whether the experiments subsystem is mounted and serving in this process.
`GET /v1/experiment`	Every experiment in the caller's org, with its variants, status and decision, ordered by project then id.
`POST /v1/experiment`	Registers a controlled experiment AND puts its assignment flag live, in that order, so the arms start bucketing subjects the moment this returns 201 — the flag is created active at 100% rollout, with each variant weighted as declared.

All Hanzo APIs · Interactive reference

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