Get all patients (no filters)
AI agents call search_all_patients 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 from a FHIR system without filtering or parameters, making it a Read action. However, severity is elevated to 'high' due to the healthcare context: unrestricted access to all patient data exposes sensitive Protected Health Information (PHI), creating significant privacy and compliance risks (HIPAA, GDPR) if misused by an AI agent.
From the tool's definition Tool name 'search_all_patients' and description 'Get all patients (no filters)' indicate a retrieval operation with no side effects. The verb 'Get' and the function of querying without modification confirm this is a Read operation.
Attacks that exploit this kind of access
Get all patients (no filters). 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_all_patients: 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_all_patients 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_all_patients 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_all_patients. 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_all_patients is provided by the FHIR MCP Server MCP server (jcafazzo/fhir-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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