get_participants_sessions
AI agents call get_participants_sessions to retrieve information from Nipoppy MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves participant and session information from a neuroimaging dataset—a read operation with no modification capability. However, severity is elevated to 'medium' rather than 'low' because the data involved is clinical/health information, which is sensitive.
From the tool's definition Tool name 'get_participants_sessions' follows the read-operation pattern consistent with sibling tools like 'get_bids_participants_sessions', 'get_dataset_info', and 'list_*' variants which all retrieve data.
Attacks that exploit this kind of access
get_participants_sessions. It is categorised as a Read tool in the Nipoppy MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Nipoppy MCP Server MCP server in PolicyLayer and add a rule for get_participants_sessions: 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 Nipoppy MCP Server. Nothing to install.
get_participants_sessions 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 get_participants_sessions 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 get_participants_sessions. 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.
get_participants_sessions is provided by the Nipoppy MCP Server MCP server (nipoppy/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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