set_glyph_unicode

THE RISK

Medium Risk

Why set_glyph_unicode needs a policy

This tool modifies glyph properties (unicode assignments) in a font file, making it a Write operation—data is created or altered reversibly. It is not Destructive (the change can be undone via undo/version control), not Execute (no code execution or external command triggering), and not Financial.

From the tool's definition Tool name 'set_glyph_unicode' and description 'Set the unicode value of a glyph' indicate modification of font glyph metadata. The server description confirms 'read and write font data directly in GlyphsApp' with 'bidirectional, real-time' capability.

Documented attack patterns abuse exactly the kind of access set_glyph_unicode gives an agent:

POLICY

How to control set_glyph_unicode

PolicyLayer is an MCP gateway — it sits between your AI agents and Glyphs, and nothing reaches the server without passing your rules. This is the rule we recommend for set_glyph_unicode:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_glyph_unicode": {
      "limits": [
        {
          "counter": "set_glyph_unicode_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

set_glyph_unicode stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

Create a free account and register Glyphs — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Glyphs tools

Destructive delete_glyph Delete a glyph from the font. This cannot be undone via MCP. Destructive delete_kerning_pair Delete a kerning pair. Execute execute_in_glyphs execute_in_glyphs Execute rmx_scale rmx_scale Write duplicate_glyph Duplicate a glyph (all layers and paths) under a new name. Write create_glyph create_glyph Write rename_glyph Rename a glyph. Fails if new_name already exists. Write set_feature_code Create or update an OpenType feature.

All 41 Glyphs tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about set_glyph_unicode

What does the set_glyph_unicode tool do? +

Set the unicode value of a glyph. It is categorised as a Write tool in the Glyphs MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_glyph_unicode? +

Register the Glyphs MCP server in PolicyLayer and add a rule for set_glyph_unicode: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Glyphs. Nothing to install.

What risk level is set_glyph_unicode? +

set_glyph_unicode is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_glyph_unicode? +

Yes. Add a rate_limit block to the set_glyph_unicode rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block set_glyph_unicode completely? +

Set action: deny in the PolicyLayer policy for set_glyph_unicode. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides set_glyph_unicode? +

set_glyph_unicode is provided by the Glyphs MCP server (nmassi/glyphs-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Glyphs tool call.

Start from Glyphs, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →