Writing code is cool, but wouldn't it be cooler to type "build me a plugin showing populations around the world" and it Just Worked? Now you can.
Video demonstration:
Requirements
Agent currently requires an API Key from OpenRouter or Anthropic / Claude. You may alternatively use our MCP Server and Agent skills with any model (see "MCP Server" section below).
Optionally, a free Tavily API key gives your agent access to web search and web page fetching, enhancing your agents capabilities.
In the near future you'll be able to purchase credits directly from TRMNL.
Quickstart
Again, a video demonstration is here.
How it works
TRMNL has developed a comprehensive system prompt written in plain English, which describe our platform's capabilities and design patterns in depth.
Whenever you interface with the Agent inside our private plugin interface, the agent has access to this context, which you may even ask it about.
In addition, the agent has been given access to a range of tools, including markup editing, settings updates, data refreshing, internet search, and a list of API endpoints to name a few. This empowers and grounds the agent in the "real world" to add value to your experience.
MCP Server (Advanced)
Prefer building plugins from your own editor with Claude, Codex, Cursor, or another AI tool?
TRMNL runs an MCP (Model Context Protocol) server at https://trmnl.com/mcp. There are two ways to connect to it:
If you're not sure, connect your account. You can limit it to a single plugin when you sign in.
Connect your account: Claude Code (CLI)
Run this in your terminal:
Start a Claude Code session, type /mcp, pick trmnl and choose to authenticate. Your browser opens a TRMNL page titled "Connect an app to your account", where you choose:
Click Allow and head back to your terminal. Then ask away: "show me my plugin's markup," "refresh my data and screenshot the full layout," and so on.
By default this registers the server for your current project folder only; add --scope user to make it available everywhere. The Claude Code desktop app reads the same configuration, so no extra setup is needed there.
Connect your account: Claude Desktop (chat app)
Connect your account: other tools
Codex, Cursor, VS Code and most other MCP clients sign in the same way. Add https://trmnl.com/mcp as an HTTP (or "streamable HTTP") server and your tool opens the TRMNL sign-in page when it first connects.
Manage connected agents
Every tool you've signed in lives under Account > Developer > Connected agents, with what it can do and when it was last active.
Connect one plugin with an MCP API Key
Then connect with the key. In Claude Code:
In Claude Desktop, add a custom connector with this URL instead: https://trmnl.com/mcp?api_key=YOUR_MCP_API_KEY
For other tools, expand "MCP client config" under the key for a ready-made config snippet, or send the key in an Authorization: Bearer header.
Agent skills
MCP gives your tool access to TRMNL. Our agent skill teaches it how to build for TRMNL: the same rules and design system docs our built-in Agent uses. Install it from github.com/usetrmnl/trmnl-agent-skills. It works with Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot and opencode. In Claude Code, run these two commands:
The install guide covers the other tools. Building your own app or script instead? trmnl.com/auth.md lists every way to authenticate with TRMNL.
Good to know
Frequently Asked Questions
Which models does this feature support?
Gemini, Codex, Claude Sonnet, Kimi, and even OSS models (e.g. Llama). Set a preferred model from your Account > Preferences > Configure model, keys & usage.
How much does it cost to build a plugin?
We're seeing an average of $1-3 per plugin.
For example, plugin can be created with a single sentence prompt: make a daily deal plugin for meh.com. After thinking and developing for a couple minutes, Agent required us to provide a free Meh.com API Key, then we requested that the daily deal item's image be included. Total cost: $2.20 USD.
Can I publish plugins with this feature?
Not currently. Our team reviews several plugin submissions per day and we need to scale internal tools before we can handle the inevitable Agent-driven volume bump.
Can I use other llm models (including free ones)?
Yes. Agent uses Claude Sonnet 5 by default, but other state-of-the-art models like Gemini 3.1 Pro are excellent replacements. Feel free to experiment with any OpenRouter model ID. The free models on OpenRouter tend to be less capable and slower.
Troubleshooting
Agent isn't perfect. Send us a live chat or email support@trmnl.com if you discover any quirks.