---
title: "Start Run"
method: POST
path: "/api/agent-chat/playground/runs"
tags: ["Agent Chat Playground"]
---

# Start Run

`POST /api/agent-chat/playground/runs`

## Cookies

- `ex_access` string, nullable
- `ex_org` string, nullable

## Request body

- ApiAgentChatPlaygroundRouterStartRunRequest — Body of ``POST /runs``. ``tool_names`` is the user's full tool allowlist (not a delta against the sub-agent's default). An empty list means "no MCP tools at all". ``cli_backend`` picks which CLI drives the run — ``'claude'`` (default) or ``'codex'``. Unknown values fall back to the global default at the worker layer rather than 4xx'ing here, so an out-of-date UI never blocks a launch.
  - `name` string, required — Sub-agent name from SUBAGENT_REGISTRY
  - `user_message` string, required
  - `model` string, nullable
  - `tool_names` string[]
  - `cli_backend` string, nullable

## Response `202`

Successful Response

- unknown

## Other responses

- `422` — Validation Error

---

[API](https://skmtc.dev/explee/apis/explee-api.md) · [All operations](https://skmtc.dev/explee/apis/explee-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/explee/explee-api/revisions/f169bc6e9447/schema)