Glyphs MCP

MCP bridge for AI-assisted type design in GlyphsApp.

Lets Claude, Cursor, or any MCP client read and write font data directly in GlyphsApp — bidirectional, real-time, live in the editor.

MCP Client  ←(stdio/MCP)→  MCP Server  ←(HTTP/localhost)→  GlyphsApp Plugin

Requirements

• GlyphsApp 3 (tested on 3.2+)
• An MCP client: Claude Code, Cursor, Windsurf, etc.
• Python 3.10+ with uv (recommended) or pip

Installation

1. Install the GlyphsApp plugin

From Plugin Manager (recommended): Open GlyphsApp, go to Window > Plugin Manager, search for MCP, and click Install.

Manual install: Download GlyphsMCP.glyphsPlugin.zip from the latest release, unzip, and double-click to install.

Restart GlyphsApp. You should see GlyphsMCP under the Window menu.

2. Connect your MCP client

Claude Code:

claude mcp add glyphs-mcp -- uvx glyphs-mcp

Cursor / VS Code — add to your MCP config:

{
  "mcpServers": {
    "glyphs-mcp": {
      "command": "uvx",
      "args": ["glyphs-mcp"]
    }
  }
}

That's it.

3. Use it

Open a font in GlyphsApp, then ask your AI assistant:

"Run a full color audit on my font and tell me which glyphs are inconsistent"

"Compare the stems across all my lowercase letters"

"Check if my figures are consistent with my letters"

"Make the R 20% wider and harmonize the curves"

"Analize metrics on lowercases"

Tools

Read

Tool	Description
get_font_info	Font family name, UPM, glyph count, masters, axes, metrics, instances
list_glyphs	All glyph names with unicode, category, layer count
get_glyph	Full glyph data: paths, components, anchors, sidebearings for all layers
get_glyph_svg	Glyph rendered as SVG markup
get_selection	Current editor selection: active glyph, layer, selected paths/nodes
get_masters	All masters with metrics and axis positions
get_kerning	All kerning pairs for a master
get_features	OpenType feature code

Write

Tool	Description
create_glyph	Create a new glyph with optional width, unicode, and initial paths
set_glyph_paths	Replace all paths on a glyph's layer
set_glyph_width	Set advance width
set_glyph_color	Set color label (0-11)
set_glyph_unicode	Assign or clear a unicode value
rename_glyph	Rename a glyph
duplicate_glyph	Copy a glyph with all layers to a new name
delete_glyph	Delete a glyph
set_kerning_pair	Add or modify a kerning pair
delete_kerning_pair	Remove a kerning pair
set_feature_code	Create or update an OpenType feature

Analysis

Tool	Description
measure_stems	Measure stem thicknesses via perpendicular ray-casting
compare_stems	Compare stems across glyphs using industry patterns
get_stem_targets	Designer's intended stem values from Dimensions palette
measure_color	Measure ink density for a single glyph
compare_color	Compare ink density across glyphs
audit_font_color	Full font color audit across all letters
check_overshoots	Overshoot consistency at baseline, x-height, cap-height
compare_proportions	Width ratios, related-form groups, ordering constraints
check_diagonal_weights	Diagonal stem thickness vs straight reference
check_junctions	Stem thinning at arch/bowl junctions
check_related_forms	Cross-validate figures and letters (0/O, 6/9, 8/S, 3/B)
check_punctuation	Mirrored pair widths, dash ratios, related punctuation
check_compatibility	Master compatibility: paths, nodes, components, anchors
analyze_kerning	Kerning quality: cross-master gaps, orphans, outliers
analyze_spacing	Spacing quality: sidebearing groups, symmetry, drift

Analysis tools automatically mark glyphs in GlyphsApp: red = inconsistent, orange = unreliable, yellow = optical compensation, green = pass.

RMX Tools

Requires RMX Tools for full functionality. Falls back to native transforms when RMX is unavailable.

Tool	Description
rmx_harmonize	Optimize bezier curves
rmx_scale	Scale by percentage with stroke weight compensation
rmx_tune	Adjust weight, width, height, or slant
rmx_monospace	Adjust a glyph to a fixed advance width
rmx_batch	Apply any RMX filter to multiple glyphs

Advanced

Tool	Description
execute_in_glyphs	Run arbitrary Python inside GlyphsApp (disabled by default)

Multi-master support

All tools accept an optional master_id parameter. When omitted, read/write tools use the first master. Analysis tools analyze all masters and return per-master results.

Menu

The plugin adds a GlyphsMCP submenu under Window in the menu bar:

• Start/Stop Server — toggle the HTTP server
• Connect — copy ready-to-paste MCP config for Claude Code or VS Code (and forks)
• Documentation — open this page in your browser
• Allow Execute Endpoint — enable execute_in_glyphs (off by default for security)

Preferences

Key	Default	Description
com.nico.glyphs-mcp.port	7745	HTTP server port
com.nico.glyphs-mcp.autostart	true	Start server on GlyphsApp launch
com.nico.glyphs-mcp.allowExecute	false	Enable the execute endpoint

How it works

The GlyphsApp plugin runs an HTTP server on 127.0.0.1:7745 inside GlyphsApp. All GlyphsApp API calls run on the main thread via a queue + NSTimer bridge for thread safety.

The MCP server is a thin translation layer — it receives MCP tool calls via stdio and forwards them as HTTP requests to the plugin.

Roadmap

• Font proofing — Generate proof strings for spacing/kerning evaluation
• Auto-update — Check for updates directly from the GlyphsMCP menu
• Analytics — Optional usage telemetry to guide development priorities

License

MIT — Nicolas Massi www.nico.works