AI agents call measure_color 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.
Although the description is empty and confidence is reduced accordingly, the tool name and the semantic pattern of sibling inspection/analysis tools suggest this retrieves or measures color properties in font glyphs without altering them. This is a read-only operation with no side effects, making it low severity. The missing description prevents higher confidence.
From the tool's definition Tool name 'measure_color' with no description provided. In the context of a font design MCP server (GlyphsApp), 'measure' typically indicates analysis or inspection without modification.
Documented attack patterns abuse exactly the kind of access measure_color 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 measure_color:
{
"version": "1",
"default": "deny",
"tools": {
"measure_color": {}
}
}measure_color is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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measure_color. 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 measure_color: 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.
measure_color 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 measure_color 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 measure_color. 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.
measure_color 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.