Get direct child terms for a given HPO term (one level down in the hierarchy)
AI agents call get_hpo_children to retrieve information from Unofficial HPO 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 and queries data from the Human Phenotype Ontology hierarchy with no side effects. It does not create, modify, delete, execute code, or commit any irreversible changes. The operation is a simple read of parent-child relationships in a static ontology database. Misuse by an AI agent would result only in unwanted information retrieval, not system damage or data loss.
From the tool's definition Tool description states 'Get direct child terms for a given HPO term' — a retrieval operation that queries hierarchical data without modification.
Attacks that exploit this kind of access
Get direct child terms for a given HPO term (one level down in the hierarchy). It is categorised as a Read tool in the Unofficial HPO MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Unofficial HPO MCP Server MCP server in PolicyLayer and add a rule for get_hpo_children: 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 Unofficial HPO MCP Server. Nothing to install.
get_hpo_children 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_hpo_children 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_hpo_children. 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_hpo_children is provided by the Unofficial HPO MCP Server MCP server (openpharma-org/hpo-mcp-server). 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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