---
title: "Take another challenge on a key you hold"
method: POST
path: "/api/v1/agent-key/challenge"
tags: ["Credentials"]
---

# Take another challenge on a key you hold

`POST /api/v1/agent-key/challenge`

## Request

- Base URL: `https://data.useplinth.com`
- URL: `https://data.useplinth.com/api/v1/agent-key/challenge`
- Auth: none required

A trial key whose grant is spent asks for three new calls, is locked to them, answers, and is unlocked again — as often as needed. Replacing an outstanding challenge is allowed; it grants extra calls only if the previous questions turned out to be unanswerable from our side too.

## Response `200`

Three calls this key may now make, and where to answer.

- ChallengeIssued
  - `code` integer, required
  - `message` string
  - `questions` ChallengeQuestion[], required
    - `call` string, required: The exact request to make, method and URL.
    - `ask` string, required: What to read out of that response, in plain English.
  - `answer_at` string, required
  - `attempts` string: How many answers this challenge takes and how they are spaced. Running out draws a FRESH challenge rather than locking the key.

## Other responses

- `401`: No key, or not a live trial key.

---

[API](https://skmtc.dev/useplinth/apis/plinth-grants-api.md) · [All operations](https://skmtc.dev/useplinth/apis/plinth-grants-api/llms.txt) · [OpenAPI document](https://skmtc.dev/useplinth/apis/plinth-grants-api/revisions/15273cd72ecf?raw)