<p align="center">
  <img src="assets/glyphs-mcp.png" alt="GlyphsMCP" width="400">
</p>

MCP bridge for AI-assisted type design in [GlyphsApp](https://glyphsapp.com).

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](https://glyphsapp.com)
- An MCP client
- Python 3.10+ with [uv](https://docs.astral.sh/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](https://github.com/nmassi/glyphs-mcp/releases/latest), 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:

```json
{
  "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:

```sh
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:

```sh
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