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

• Glyphs 3 or 4
• An MCP client
• Python 3.10+ with uv (recommended) or pip
• glyphsets and shaperglot (installed automatically with the MCP package)

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

Open Window > GlyphsMCP > Connect and choose your client:

• Claude Code — registers a user-scoped stdio server with the official claude CLI.
• Codex / ChatGPT Desktop — registers the server with codex; both apps share this configuration.
• OpenCode — adds the server to OpenCode's global configuration; restart OpenCode afterward.
• Visual Studio Code — adds the server to your active user profile with code --add-mcp.
• Cursor — safely merges the server into ~/.cursor/mcp.json and backs up an existing file first.
• Other MCP Client — copies a portable mcpServers JSON block to the clipboard.

Glyphs 4 registers as glyphs-mcp and Glyphs 3 as glyphs-mcp-3, each using the port configured in that app, so both can stay registered without collision. If a client CLI is not available to GlyphsApp, the equivalent Terminal command is copied to the clipboard instead.

For manual setup, use the endpoint shown when starting the GlyphsMCP server. For example:

{
  "mcpServers": {
    "glyphs-mcp": {
      "command": "uvx",
      "args": ["glyphs-mcp"],
      "env": {
        "GLYPHS_URL": "http://127.0.0.1:7746"
      }
    }
  }
}

Claude Desktop now recommends Desktop Extensions (.mcpb) for local MCP servers. A GlyphsMCP Desktop Extension is planned separately and is not installed by this menu yet.

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	Glyph metadata, optionally filtered by category and capped by limit
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	Kerning pairs filtered by master_id/left, optionally capped by limit
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
generate_box_drawing	Generate U+2500–U+259F outlines across masters; can overwrite drawings
export_font	Export OTF, TTF, WOFF, WOFF2, and variable TTF beside the saved source

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
analyze_kerning_groups	Analyze or assign kerning groups, with dry-run/overwrite control
auto_kern	Preview or apply optical-area kerning to critical, automatic, or explicit pairs
check_glyphset_coverage	Check Google Fonts glyphsets and optionally add missing empty glyphs
check_language_support	Export a temporary instance and evaluate language support with Shaperglot
review_production	Run a 44-item production-readiness review
check_font_name	Screen a proposed family name against Fontdata; not legal clearance

Analysis tools never change glyph colors by default. Pass mark_glyphs=True only when you explicitly want verdict labels in GlyphsApp: red = inconsistent, orange = unreliable, yellow = warning/optical compensation, green = pass. analyze_kerning, analyze_spacing, check_compatibility, and compare_stems also point to matching workflow recipes for broader checks.

RMX Tools

Requires RMX Tools for full functionality. rmx_scale now uses real RMX processing, accepts one value or a per-master list for scale parameters, and defaults allow_fallback=False; native affine fallback must be explicitly enabled. rmx_tune delegates to the loaded RMX Tuner and supports blend and all_masters.

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
smart_scale	Scale multiple glyphs with measured stem compensation, optional backups

Recipes

Bundled markdown recipes provide ordered workflows for consistency audits, spacing, kerning, master compatibility, proportional scaling, dated-layer cleanup, and Glyphs plugin or script creation.

Tool	Description
list_recipes	List bundled and user-created recipes
get_recipe	Read a complete recipe
get_recipe_step	Read one numbered step with its next-step directive
create_recipe	Write a recipe markdown file; overwrite is opt-in
delete_recipe	Permanently delete a recipe markdown file

Recipe creation and deletion modify files in the installed plugin's Resources/recipes directory.

Recipes are also exposed as MCP prompts, so clients that surface prompts as commands get a one-command entry point. The prompt name is the recipe name. With the server registered as glyphs-mcp, a recipe runs as /glyphs-mcp:<recipe> or /mcp__glyphs-mcp__<recipe>:

Recipe	Command (Claude Code)	What it does
audit_consistency	/glyphs-mcp:audit_consistency	Full font consistency audit: stems, color, proportions, spacing
spacing_workflow	/glyphs-mcp:spacing_workflow	Systematic spacing pass following Cheng/Briem/Ruder
kerning_from_scratch	/glyphs-mcp:kerning_from_scratch	Kerning from scratch: groups, critical pairs, verification
scale_proportions	/glyphs-mcp:scale_proportions	Scale glyphs with automatic stem-weight compensation
master_compatibility	/glyphs-mcp:master_compatibility	Pre-export master compatibility and metrics check
cleanup_dated_layers	/glyphs-mcp:cleanup_dated_layers	Safely remove timestamped backup layers
create_glyphs_plugin	/glyphs-mcp:create_glyphs_plugin	Create a GlyphsApp plugin bundle
create_glyphs_script	/glyphs-mcp:create_glyphs_script	Create a GlyphsApp Script-menu script
recipes	/glyphs-mcp:recipes	List the available recipes, or start one by name

These forms are what Claude Code uses. On Glyphs 3 the server prefix is glyphs-mcp-3 (for example /glyphs-mcp-3:audit_consistency), so both apps can be registered side by side. MCP-prompt support varies by client: if yours does not surface prompts as commands, ask for the recipe by name or use list_recipes / get_recipe / get_recipe_step. In opencode you can add a custom command under .opencode/commands/ (or ~/.config/opencode/commands/) that calls get_recipe_step to get a literal /create-plugin.

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.

Tools with side effects are explicit: kerning-group analysis can assign groups, while audit color labels require mark_glyphs=True; auto-kern can write kerning; glyphset coverage can add empty blue-labelled glyphs; box drawing creates or replaces outlines; smart scale modifies outlines and can create backup layers; recipe CRUD writes or deletes markdown files. export_font writes a new timestamped directory under export/ beside the saved source and never removes previous exports. Use dry-run/preview options where available and save the font before bulk operations.

Font export

Ask the agent to export the open font, or run the bundled CLI directly:

uvx --from glyphs-mcp export-glyphs /path/to/MyFont.glyphs

Both paths use the official glyphs-cli, installed automatically with the GlyphsMCP server package on macOS. Glyphs Plugin Manager installs only the app plugin; uvx glyphs-mcp provisions the server and export CLI on first use. Each run creates export/YYYY-MM-DD_HH-MM-SS/ beside the source, with separate otf, ttf, woff, woff2, and variable directories as applicable, plus export-report.jsonl. The MCP tool refuses to export unsaved changes unless save_before_export=True is explicitly requested. Every result includes portable exportLog and ANSI-colored exportLogAnsi variants; the calling agent must show the colored variant when its client supports terminal colors and fall back to the portable log elsewhere.

Menu

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

• Start/Stop Server — toggle the HTTP server
• Connect — register GlyphsMCP with Claude Code, Codex/ChatGPT Desktop, OpenCode, VS Code, Cursor, or copy a generic configuration
• 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 using the configured port (7745 by default). 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 to the plugin URL supplied through GLYPHS_URL.

Bundled agent skill

Python distributions include the complete skills/type-designer/ skill: a concise runtime contract plus references for general type-design workflows, typeface DNA, Glyphs 4 and scripting, safe GlyphsMCP operation, the audit contract, and curve-continuity evidence. GlyphsMCP is one execution environment within the skill, not its only subject.

The skill is not installed automatically or served live through SEP-2640 because the current Python MCP SDK does not expose that extension. Install the directory through your client's normal skill workflow. To keep this checkout as the single source of truth, link rather than copy it into each client's discovery directory:

ln -s "/path/to/glyphs-mcp/skills/type-designer" "$HOME/.codex/skills/type-designer"
ln -s "/path/to/glyphs-mcp/skills/type-designer" "$HOME/.claude/skills/type-designer"
ln -s "/path/to/glyphs-mcp/skills/type-designer" "$HOME/.config/opencode/skills/type-designer"

Every client then discovers the same physical skill through SKILL.md; no separate copies diverge.

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