AI agents call list_allergies to retrieve information from Healow without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and queries patient allergy data from the FHIR API without creating, modifying, or deleting any records. While the data retrieved (patient allergies) is clinically sensitive and could enable harmful actions if misused by an agent (e.g., recommending contraindicated medications), the tool itself performs only read-only operations.
From the tool's definition Tool name 'list_allergies' and description 'List AllergyIntolerance resources' indicate a retrieval operation with no modification or deletion of data. The verb 'list' is a standard Read operation.
Attacks that exploit this kind of access
List AllergyIntolerance resources for the launch patient. It is categorised as a Read tool in the Healow MCP Server, which means it retrieves data without modifying state.
Register the Healow MCP server in PolicyLayer and add a rule for list_allergies: 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 Healow. Nothing to install.
list_allergies 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 list_allergies 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 list_allergies. 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.
list_allergies is provided by the Healow MCP server (voysi-ia/healow-mcp-server). 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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