MCP (Model Context Protocol) is a tools & integrations option for building AI agents. The open protocol for exposing tools and data to agents. The default answer.
Worth knowing. Write your integrations as MCP servers and every harness on this page can use them unchanged.
npm install @modelcontextprotocol/sdk
| Option | What it does | Licence | Self-host |
|---|---|---|---|
| MCP (Model Context Protocol) | The open protocol for exposing tools and data to agents. The default answer. | Open source | Yes |
| Composio | Managed auth and tool-calling for 250+ SaaS apps. | Open source | No |
| Arcade | Tool-calling with per-user OAuth, so the agent acts as the user, not as root. | Open source | Yes |
| Browserbase | Managed headless browsers with stealth and session replay, plus Stagehand. | Proprietary | No |
| Playwright MCP | Drive a real local browser over MCP, using the accessibility tree. | Open source | Yes |
| Nango | Open-source integration platform — you own the OAuth and the sync logic. | Open source | Yes |
Every page here answers to Accept: text/markdown and returns the same content at roughly a tenth the tokens. No separate site, no toggle — same URL.
curl -s -H "Accept: text/markdown" https://newagent.build/c/mcp