Search for patients by address components.
AI agents call search_patients_by_address to retrieve information from FHIR MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves patient records based on address criteria. While it performs a read-only operation (no side effects), the severity is elevated to 'medium' rather than 'low' because it exposes access to sensitive healthcare personally identifiable information (PII) including patient addresses.
From the tool's definition Tool name 'search_patients_by_address' and description 'Search for patients by address components' indicate a query/retrieval operation with no modification or deletion capability.
Attacks that exploit this kind of access
Search for patients by address components. It is categorised as a Read tool in the FHIR MCP Server MCP Server, which means it retrieves data without modifying state.
Register the FHIR MCP Server MCP server in PolicyLayer and add a rule for search_patients_by_address: 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 FHIR MCP Server. Nothing to install.
search_patients_by_address 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 search_patients_by_address 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 search_patients_by_address. 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.
search_patients_by_address is provided by the FHIR MCP Server MCP server (sdesani/mcp-fhir). 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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