MCP: Connect AI Apps

Throughline can work with the AI app you already use. Turn on the connection, and Claude Desktop, Claude Code, Cursor or any other app that speaks the Model Context Protocol (MCP) can read your open project and work on it with you: plan Beats, build Characters and Settings, arrange piles, set Arc charges, lay out the Constellation and write scenes.

You watch every change happen live in the app, and you can undo each one.

Off until you turn it on

The connection is off by default. Turn it on under Settings → AI → MCP: Connect AI Apps → Allow connections. The status line shows when it’s running.

This is separate from the AI Assistant. You can use either one, both, or neither.

Connect Claude Desktop

1. Turn on Allow connections.
2. Click Add to Claude Desktop.
3. Restart Claude Desktop.

Claude now lists Throughline among its tools. Ask it something like “Read my project in Throughline and suggest where the second act sags.”

On a Mac, move Throughline to your Applications folder first and open it from there. Throughline tells you if it needs this.

If Add to Claude Desktop can’t find Claude Desktop, click Copy config, then open Claude Desktop’s Settings → Developer → Edit Config and paste the Throughline entry into mcpServers.

Connect Claude Code, Cursor and other apps

• Claude Code: click Copy Claude Code command and run it in your terminal.
• Cursor and other MCP apps: click Copy config and paste it into the app’s MCP settings.

Permissions

Throughline gives AI apps three tools: one to read the project, one to edit it, and one to open another project. Claude Desktop asks you once for each tool the first time it’s used, so you’ll see at most three prompts.

In Claude Code, you can allow all three at once: run /permissions and add the rule mcp__Throughline.

How it works

• Throughline must be running. The AI app talks to the open app, not to your files. If Throughline is closed, the AI app says so.
• It works on the open project. The AI app can list your recently opened projects and open another one, the same way you would from the Home screen.
• Every change is yours to keep or undo. The AI app sends its edits in batches, and each batch is one undo step. Press Cmd+Z (Ctrl+Z on Windows) to take it back. The AI app can also take back its own last batch, as long as you haven’t edited since. If one edit in a batch can’t be made, Throughline makes none of them. Switching projects clears the undo history, as usual.
• Layout never blocks your story edits. If the AI app can’t lay out the Constellation or an Arc cleanly, it gets a warning and keeps the rest of the batch.
• Changes save like your own edits. They land in your .thrl file through autosave.
• Your typing wins. If the AI app writes into the scene you’re typing in, your unsaved typing is kept. Undo brings the AI’s version back if you want it.

Easy for AI apps to use

• The rules come with the tools. Each tool explains Throughline’s story model, so the AI app knows how Beats, piles, relationships and Arcs work from its first call.
• Names in, names out. The AI app refers to Beats by number or title and to Characters, Settings and Arcs by name, as you do. When a name fits more than one card, Throughline lists the candidates instead of guessing.
• The whole timeline. The AI app sees when each relationship starts, how its feelings change and where it ends.
• Clear results. Each edit reports what changed, including the feelings it replaced, so the AI app can explain its work to you.

What the AI app can do

• Read: the project overview, Beats in story order, full scene text, Characters and how their relationships change across the story, Settings with their piles, Arcs and charges, Sparks, and the recycling bin.
• Create and edit: Beats, Characters, Settings, Sparks, structure cards, project details and relationships. It writes scenes in Fountain for screenplay projects and in prose for rich text projects, and it can fix a single word or line without rewriting the scene. Your formatting stays as it is.
• Arrange: move Beats and structure cards, pile and unpile them, reorder Settings and Characters.
• Recycle and restore: send cards to the recycling bin and bring them back.
• Shape: create Arcs, add or remove Beats, set emotional charges, and space an Arc’s Beats evenly again.
• Constellation: lay out the cast by Throughline’s layout rule or move single Characters. It checks that no two Characters or relationship labels cover each other.

Privacy

The connection stays on your computer. Throughline opens it only to apps running on the same machine, and only while the switch is on.

The AI app you connect is a separate program. What it reads from your project goes to its own AI provider under that app’s terms. For example, Claude Desktop sends it to Anthropic.

Browser-based apps such as claude.ai or ChatGPT on the web can’t reach a desktop app, so they can’t connect.

Troubleshooting

• “Throughline is not running, or its MCP connection is off.” Open Throughline and check that Allow connections is on.
• “Throughline did not answer in time.” If Throughline’s window is minimized or hidden, bring it to the front and try again.
• “No project is open.” Open a project in Throughline, or ask the AI app to open one.
• “Throughline is asking the writer about a file change.” Your .thrl file changed outside the app. Answer the dialog in Throughline, then try again.