update_fhir_resource · Awslabs Valkey MCP: Risk & Policy

WHAT IT DOES

What update_fhir_resource does on Awslabs Valkey

AI agents use update_fhir_resource to create or update resources in Awslabs Valkey — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Awslabs Valkey environment.

WHY IT NEEDS A POLICY

Why update_fhir_resource needs a policy

This tool modifies existing FHIR (healthcare) resources in AWS HealthLake, a protected health information (PHI) system. While update operations are reversible (classifying as Write rather than Destructive), the target is sensitive medical data in a regulated healthcare system. Misuse could alter patient records, clinical notes, or treatment history.

From the tool's definition Tool name is 'update_fhir_resource' and description states 'Update an existing FHIR resource in HealthLake', indicating modification of healthcare data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_fhir_resource Rate-limited

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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "update_fhir_resource": {
      "limits": [
        {
          "counter": "update_fhir_resource_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Awslabs Valkey, so you can run agents against it safely.

FAQ

Questions about update_fhir_resource

What does the update_fhir_resource tool do? +

Update an existing FHIR resource in HealthLake. It is categorised as a Write tool in the Awslabs Valkey MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_fhir_resource? +

Register the Awslabs Valkey 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 Awslabs Valkey. Nothing to install.

What risk level is update_fhir_resource? +

update_fhir_resource is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit update_fhir_resource? +

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.

How do I block update_fhir_resource completely? +

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.

What MCP server provides update_fhir_resource? +

update_fhir_resource is provided by the Awslabs Valkey MCP server (awslabs.valkey-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.