Sheet Music in InDesign, as if It Were Always There

InDesign has no idea what a musical score is. No staff, no bar line, nothing that knows a crotchet from a bullet point. Music gets into a layout the way it has for decades: a notation program exports a PDF, and someone places it, page by page, into frames.

Two things go wrong every time. The PDF pages are never the size of your type area, so each one gets cropped, scaled and nudged into place by hand, and the margins never quite agree with the rest of the book. And the music arrives with its own typography: the lyrics, the tempo marks, the title over the first system are set in whatever the notation program defaulted to, while the book around them is set in something else. The page looks like two typesetters worked on it without ever meeting—and in a sense they did.

Here is Claude fixing both at once. Schubert’s An den Mond, four pages of music, engraved with GNU LilyPond and laid out in InDesign with a title page, running heads and page numbers. Every page of music fills the type area exactly, and every word inside the music is in the same Minion Pro as the poem on the title page. Nobody measured anything.

That is pages 2 and 3 of the finished PDF, exported from InDesign—six pages, title page to colophon.

How it works

Two MCP servers, one conversation. Sidekick connects Claude to InDesign; lilypond-mcp lets it engrave LilyPond source into a PDF, with nothing to install.

The score fits the page. Instead of making the music fit the layout after the fact, Claude makes the layout the music’s paper. It asks the InDesign document for its margins, works out the type area—172 × 252 mm here—and tells LilyPond that this is its page size, with no margins, headers or page numbers of its own. Every page LilyPond engraves is then exactly the size of the area between the margins, and page one of the score goes on page two of the document, page two on page three, and so on, mirrored for left and right pages. No cropping, no scaling, no coordinates. LilyPond decides where the page turns fall; InDesign supplies everything around the music.

The score speaks the book’s font. Claude asks the document which font its body text uses—and then asks that font where it lives. InDesign knows the path of every font file it has loaded, and Sidekick passes it on. Claude hands the folder to LilyPond, and the lyrics come out in Minion Pro. Nobody copied a font, nobody typed a path.

This is what that changes. The top is LilyPond on its own; the bottom is the same two bars once Claude had given it the document’s font.

The top one isn’t ugly. Next to a page of Minion Pro it’s a different book.

What you say

All of it comes from one prompt:

The song in score.ly has to go into the open document between the title page and the colophon, one engraved page per document page, with the A-Music parent applied to the new pages. Engrave it with LilyPond so that each PDF page is exactly the size of this document’s type area, with no margins, headers or page numbers of its own—InDesign supplies those. Set the text in the score in the same font as the document’s Body style: find out which font file InDesign loads for it and give that folder to LilyPond.

Claude reads the document, engraves, checks the preview, inserts the pages, places the score and takes a snapshot of a spread to see that the running heads and the music line up. Then it’s your document again.

The starting document, the LilyPond source, the prompt and the finished InDesign file are in the sidekick-examples repository, along with the handful of LilyPond details Claude had to work out along the way—so the next run doesn’t have to.