query_instances
AI agents call query_instances to retrieve information from DICOM MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool performs a query against DICOM instances, which is a read-only operation that retrieves metadata or references to medical imaging data without modification. However, severity is elevated to medium due to the sensitive nature of patient medical imaging data—unauthorized access could expose protected health information (PHI).
From the tool's definition Tool name 'query_instances' paired with server pattern of query_patients, query_series, query_studies indicates a retrieval operation on medical imaging data (DICOM instances). The server explicitly supports 'query' and 'read' operations on PACS/VNA systems.
Attacks that exploit this kind of access
query_instances. It is categorised as a Read tool in the DICOM MCP Server MCP Server, which means it retrieves data without modifying state.
Register the DICOM MCP Server MCP server in PolicyLayer and add a rule for query_instances: 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 DICOM MCP Server. Nothing to install.
query_instances 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 query_instances 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 query_instances. 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.
query_instances is provided by the DICOM MCP Server MCP server (y5ive9ine/dicom-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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