delete_glyph

THE RISK

Critical Risk

Why delete_glyph needs a policy

The tool permanently removes font data (glyphs) with no undo capability. This is irreversible data loss, meeting the definition of Destructive category. High severity because deleting glyphs from a font design project could corrupt the font file and erase significant design work.

From the tool's definition Tool name is "delete_glyph" and description explicitly states "Delete a glyph from the font. This cannot be undone via MCP."

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

POLICY

How to control delete_glyph

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 delete_glyph:

policy.json

{
  "version": "1",
  "default": "deny",
  "hide": [
    "delete_glyph"
  ]
}

delete_glyph disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

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.

RESTRICT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Glyphs tools

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. Write set_glyph_color Set the color label of a glyph in the font view.

All 41 Glyphs tools →

Destructive tools on other servers

Android Forensics ADB MCP Server create_full_backup 0xarchive web3_revoke_key Frida Game Hacking MCP clear_scan cPanel MCP Server clear_spam_box

Go deeper

Critical-risk tools in Glyphs → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Blast radius → How much damage one compromised or confused agent can do — and how to bound it.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about delete_glyph

What does the delete_glyph tool do? +

Delete a glyph from the font. This cannot be undone via MCP. It is categorised as a Destructive tool in the Glyphs MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on delete_glyph? +

Register the Glyphs MCP server in PolicyLayer and add a rule for delete_glyph: 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 delete_glyph? +

delete_glyph is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit delete_glyph? +

Yes. Add a rate_limit block to the delete_glyph 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 delete_glyph completely? +

Set action: deny in the PolicyLayer policy for delete_glyph. 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 delete_glyph? +

delete_glyph 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 →