Get kerning pairs for a specific master (or first master if not specified).
AI agents call get_kerning to retrieve information from Glyphs without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves kerning pair data from a font master. No side effects are performed; the operation is purely informational and does not create, modify, delete, or execute anything. It falls squarely into the Read category with low severity since unauthorized access to font metrics poses minimal risk.
From the tool's definition Tool name is 'get_kerning' and description states 'Get kerning pairs for a specific master' — uses the verb 'Get', indicating retrieval of data without modification.
Documented attack patterns abuse exactly the kind of access get_kerning gives an agent:
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 get_kerning:
{
"version": "1",
"default": "deny",
"tools": {
"get_kerning": {}
}
}get_kerning is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get kerning pairs for a specific master (or first master if not specified). It is categorised as a Read tool in the Glyphs MCP Server, which means it retrieves data without modifying state.
Register the Glyphs MCP server in PolicyLayer and add a rule for get_kerning: 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.
get_kerning is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get_kerning 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.
Set action: deny in the PolicyLayer policy for get_kerning. 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.
get_kerning 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.
Start from Glyphs, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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41 Glyphs tools catalogued and risk-classified — across an index of 43,000+ MCP servers.