Update an existing FHIR resource in HealthLake
AI agents use update_fhir_resource to create or update resources in Amazon Location Service MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Amazon Location Service MCP Server environment.
This tool creates or modifies data reversibly within a healthcare system. While updates are theoretically reversible (unlike deletive operations), the high severity reflects the critical nature of healthcare data—incorrect or malicious updates to FHIR resources could affect patient records, medical history, treatment plans, and care delivery.
From the tool's definition Tool name 'update_fhir_resource' and description 'Update an existing FHIR resource in HealthLake' indicate modification of healthcare data stored in AWS HealthLake.
Documented attack patterns abuse exactly the kind of access update_fhir_resource gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Amazon Location Service MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for update_fhir_resource:
{
"version": "1",
"default": "deny",
"tools": {
"update_fhir_resource": {
"limits": [
{
"counter": "update_fhir_resource_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
} update_fhir_resource stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Update an existing FHIR resource in HealthLake. It is categorised as a Write tool in the Amazon Location Service MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Amazon Location Service MCP Server MCP server in PolicyLayer and add a rule for update_fhir_resource: 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 Amazon Location Service MCP Server. Nothing to install.
update_fhir_resource is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the update_fhir_resource 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 update_fhir_resource. 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.
update_fhir_resource is provided by the Amazon Location Service MCP Server MCP server (awslabs.aws-location-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Amazon Location Service MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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805 Amazon Location Service MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.