Shift

Shift is a desktop font editor. An agent can reach it in two ways; pick by where the font is.

The font is…	Use	Read
Open in the running Shift app, or the user means "what I'm looking at"	The local MCP server (shift.describe, shift.execute, shift.capture)	references/mcp.md
A saved file (.shift, UFO, Designspace, Glyphs, TTF, OTF), a batch job, or CI	shift-cli	references/cli.md

For vocabulary and conventions shared by both, read references/fonts.md; for axes, masters, instances, and interpolation, read references/variable-fonts.md.

To change how Shift itself looks (its colors, a theme, or the user's rice), edit the theme files in its config folder; read references/themes.md.

Rules

• The live MCP is read-only. It inspects, resolves, renders, and captures; it cannot change a font. To change a font, save it in Shift and edit the file with shift-cli, or describe the change for the user to make. Never claim an edit happened through MCP.
• A saved file does not include unsaved app edits. Say so when the answer depends on which one you read.
• Check exact signatures at the source. For the MCP API, call shift.describe; for the CLI, run shift-cli --help and shift-cli <command> --help. This skill describes workflows and interpretation, not every parameter.
• Target explicitly. Use the windowId from shift.sessions.list(). If a window or session disappears, list sessions again and say so; never silently switch to another font.
• Report transient state. An editor mid-drag or with edits still applying is not settled; say so when it affects the answer.
• Preview sessions are read-only. A font opened as a preview has no authored layers to read or edit.
• Look before you judge. To assess how a glyph looks, render it (shift.layers.render) or capture the editor (shift.capture) and inspect the image. Do not claim a shape looks right from coordinates alone.

If the MCP server is unreachable

Shift serves MCP only while Settings → Agents → Allow agent connections is on, and only while the app is running. Each build (Shift, Nightly, Dev) has its own server name and port; the Agents panel shows the exact setup command. Ask the user to turn it on rather than guessing ports.