getObservationById

THE RISK

Low Risk

Why getObservationById needs a policy

This tool performs a GET operation on healthcare data (FHIR observation resource), returning existing information without creating, modifying, deleting, or executing external operations. The retrieval of medical observations poses minimal risk when accessed by an AI agent, though access controls and patient privacy considerations should be evaluated separately.

From the tool's definition Tool name 'getObservationById' and description 'Retrieves an observation by its unique ID' indicate a data retrieval operation with no side effects.

Documented attack patterns abuse exactly the kind of access getObservationById gives an agent:

POLICY

How to control getObservationById

PolicyLayer is an MCP gateway — it sits between your AI agents and Medplum MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for getObservationById:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "getObservationById": {}
  }
}

getObservationById is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Medplum MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Medplum MCP Server tools

Write createCondition Creates a new condition or diagnosis for a patient. Requires a patient ID and a condition Write createEncounter Creates a new encounter (patient visit). Requires patient ID and status. Write createEpisodeOfCare Creates a new episode of care for a patient. Requires patient ID and status. Write createMedication Creates a new medication resource. Requires medication code or identifier. Write createMedicationRequest Creates a new medication request (prescription). Requires patient ID, medication reference Write createObservation Creates a new observation (lab result, vital sign, etc.). Requires patient ID and code. Write createOrganization Creates a new organization (e.g., hospital, clinic). Requires organization name. Write createPatient Creates a new patient resource. Requires first name, last name, and birth date.

All 37 Medplum MCP Server tools →

Read tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about getObservationById

What does the getObservationById tool do? +

Retrieves an observation by its unique ID. It is categorised as a Read tool in the Medplum MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on getObservationById? +

Register the Medplum MCP Server MCP server in PolicyLayer and add a rule for getObservationById: 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 Medplum MCP Server. Nothing to install.

What risk level is getObservationById? +

getObservationById is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit getObservationById? +

Yes. Add a rate_limit block to the getObservationById 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 getObservationById completely? +

Set action: deny in the PolicyLayer policy for getObservationById. 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 getObservationById? +

getObservationById is provided by the Medplum MCP Server MCP server (rkirkendall/medplum-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Medplum MCP Server tool call.

Start from Medplum MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →