Create datasets

Writes a dataset — the named set of graded examples a run scores a model against — under the caller's org and answers 201 with it.

POST /v1/eval/datasets

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Address	`https://api.hanzo.ai/v1/eval/datasets`
Method	`POST`
Operation	`post_eval_datasets`
Auth	`Authorization: Bearer $HANZO_API_KEY`

Writes a dataset — the named set of graded examples a run scores a model against — under the caller's org and answers 201 with it.

The NAME is the key, not an id: posting a name the org already has updates that dataset's description and metadata and keeps its original creation time, so this is create-or-edit and never a duplicate. Its items are untouched.

Requires a validated principal; 401 without one. The org comes from the validated owner claim, never from a client X-Org-Id, so a dataset can only ever be written under the caller's own tenant. A description over 64 KiB is 400.

Request

4 fields, body application/json (required).

Field	In	Type	Required	Description
`description`	body	string	—	Description is free text about what this set measures; over 64 KiB is refused.
`metadata`	body	object	—	Metadata is a free-form object stored with the set and echoed back verbatim.
`metadata.*`	body	any	—
`name`	body	string	yes	Name is the dataset's org-unique handle and the segment that will address it, so it must match ^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$.

Response

Status	Body	Meaning
`201`	eval.datasetView	created
`default`	problem-details	refused

201 body — 7 fields.

Field	In	Type	Always	Description
`createdAt`	body	string	—	CreatedAt is when the name was first written, kept across later edits.
`description`	body	string	—	Description is free text the org wrote about what this set measures.
`items`	body	integer (int64)	—	Items is how many examples the set holds.
`metadata`	body	object	—	Metadata is the free-form object stored with the set, echoed back verbatim.
`metadata.*`	body	any	—
`name`	body	string	—	Name is the dataset's org-unique handle and the segment that addresses it.
`updatedAt`	body	string	—	UpdatedAt is when the description or metadata last changed.

Failure carries the platform error shape — see Errors.

Examples

CLI

SDK

HTTP

MCP

hanzo eval datasets create --name <name>

.ts

.py

.go

.rs

.java

import { Configuration, EvalApi } from 'hanzoai';

const api = new EvalApi(new Configuration({ accessToken: process.env.HANZO_API_KEY }));
const { data } = await api.postEvalDatasets({ name: "<name>" });

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

client = ApiClient(Configuration(access_token=os.environ["HANZO_API_KEY"]))
result = EvalApi(client).post_eval_datasets(name="<name>")

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

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

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

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

let result = eval_api::post_eval_datasets(&cfg, Default::default()).await?;

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

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

var result = new EvalApi(client).postEvalDatasets();

curl -X POST https://api.hanzo.ai/v1/eval/datasets \
  -H "Authorization: Bearer $HANZO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
       "name": "<name>"
     }'

MCP reaches eval through the eval tool, which names its 16 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_eval_datasets"
         }
       }
     }'

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