AI agents call fhir_get 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 FHIR clinical data by resource type and ID. It performs a read-only query operation returning existing data without side effects. While the data retrieved may be sensitive (patient clinical information), the tool itself has no capability to modify, delete, or execute operations. The severity is low because misuse would only expose existing data, not cause irreversible changes or financial harm.
From the tool's definition Tool name 'fhir_get' and description 'Read any FHIR resource by type and id. Returns the raw resource.' explicitly indicate a retrieval operation with no modification or deletion capability.
Attacks that exploit this kind of access
Read any FHIR resource by type and id. Returns the raw resource. 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 fhir_get: 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.
fhir_get 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 fhir_get 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 fhir_get. 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.
fhir_get 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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