AI agents call genes_for_cell_type to retrieve information from Millimap without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool reads and returns existing cluster annotations and marker information for a specified cell type. It does not modify, create, execute, or delete any data. This is a straightforward query/lookup operation with minimal blast radius if misused.
From the tool's definition "Find which clusters are annotated as a given cell type, with their markers" — purely retrieves/queries existing annotation and marker data with no side effects.
Attacks that exploit this kind of access
Find which clusters are annotated as a given cell type, with their markers. It is categorised as a Read tool in the Millimap MCP Server, which means it retrieves data without modifying state.
Register the Millimap MCP server in PolicyLayer and add a rule for genes_for_cell_type: 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 Millimap. Nothing to install.
genes_for_cell_type 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 genes_for_cell_type 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 genes_for_cell_type. 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.
genes_for_cell_type is provided by the Millimap MCP server (milliomics/millimap-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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