# StefanBrain Developer API

> REST and MCP access to StefanBrain, the agentic copywriting platform. Send chat requests, call tools, poll jobs, and run full agents. MCP is included in every plan; REST usage bills per token against a prepaid API wallet that your plan funds with monthly credit.

Authenticate each request with an API key (`Authorization: Bearer stefan_sk_...` or `x-api-key`). Create keys in Settings → Developers. Each plan, and the trial, has API access. MCP is included in each plan (bills plan usage); REST usage bills the prepaid API wallet, which each plan funds with monthly credit.

## Docs

- [Full documentation](https://stefanbrain.com/llms-full.txt): all docs sections as one markdown file. Get this file to implement an integration.
- [OpenAPI 3.1 spec](https://stefanbrain.com/api/developers/v1/openapi): the machine-readable contract for each v1 endpoint. No auth is necessary.
- [Overview](https://stefanbrain.com/docs#overview): What the API gives you, and which surface to use.
- [Quick Start](https://stefanbrain.com/docs#quick-start): Send your first request with one curl command.
- [Authentication](https://stefanbrain.com/docs#authentication): Create keys, send them safely, and restrict each key.
- [Pricing](https://stefanbrain.com/docs#pricing): What your plan includes, per-token rates, and the wallet.
- [Rate Limits](https://stefanbrain.com/docs#rate-limits): Throughput for each plan, automatic upgrades, and 429 responses.
- [Models](https://stefanbrain.com/docs#models): Runs execute the product model. There is no model parameter.
- [Attachments](https://stefanbrain.com/docs#attachments): Upload files with multipart run requests.
- [Structured Outputs](https://stefanbrain.com/docs#structured-outputs): Get JSON that matches your schema.
- [Sync & Polling](https://stefanbrain.com/docs#async-requests): Wait for a run in one request, or poll for the result.
- [Tools](https://stefanbrain.com/docs#tools): List and call each platform tool directly.
- [Jobs](https://stefanbrain.com/docs#jobs): Poll and control long tool jobs.
- [Agent Runs](https://stefanbrain.com/docs#agent-runs): Run full tool-enabled StefanBrain agents.
- [MCP](https://stefanbrain.com/docs#mcp): Connect Claude, ChatGPT, Cursor, or any MCP client — included in every plan.
- [For Agents & Tooling](https://stefanbrain.com/docs#agents-tooling): Machine-readable docs, OpenAPI, and agent briefs.
- [Errors](https://stefanbrain.com/docs#errors): What each non-success response means.
- [Examples](https://stefanbrain.com/docs#examples): Reference requests for common flows.

## Optional

- [MCP endpoint](https://stefanbrain.com/api/developers/v1/mcp): connect an MCP client (streamable HTTP; OAuth or API-key auth).