AI agents call check_punctuation 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.
The tool appears to perform font quality checks or analysis on punctuation glyphs, consistent with sibling tools like check_compatibility, check_overshoots, and audit_font_color. These are all read operations that inspect font data without modifying it.
From the tool's definition Tool name 'check_punctuation' suggests analysis/validation of punctuation marks in font data. No description provided, but the 'check_' prefix and pattern of sibling tools (analyze_*, check_*) indicate read-only inspection operations.
Documented attack patterns abuse exactly the kind of access check_punctuation 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 check_punctuation:
{
"version": "1",
"default": "deny",
"tools": {
"check_punctuation": {}
}
}check_punctuation is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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check_punctuation. 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 check_punctuation: 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.
check_punctuation 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 check_punctuation 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 check_punctuation. 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.
check_punctuation 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.