AI agents call get_column_values to retrieve information from AACT Clinical Trials 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 column values from the AACT clinical trials database. Despite the empty description, the naming convention and peer tools strongly suggest a read-only query operation with no side effects. The worst-case scenario is unauthorized access to publicly-available clinical trial metadata, which poses minimal risk compared to write/execute/destructive categories.
From the tool's definition Tool name 'get_column_values' and sibling tools like 'fetch_rows', 'read_query', 'list_tables', and 'describe_table' all indicate data retrieval operations.
Documented attack patterns abuse exactly the kind of access get_column_values gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and AACT Clinical Trials MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for get_column_values:
{
"version": "1",
"default": "deny",
"tools": {
"get_column_values": {}
}
}get_column_values is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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get_column_values. It is categorised as a Read tool in the AACT Clinical Trials MCP Server MCP Server, which means it retrieves data without modifying state.
Register the AACT Clinical Trials MCP Server MCP server in PolicyLayer and add a rule for get_column_values: 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 AACT Clinical Trials MCP Server. Nothing to install.
get_column_values 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_column_values 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_column_values. 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_column_values is provided by the AACT Clinical Trials MCP Server MCP server (navisbio/aact_clinicaltrials_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from AACT Clinical Trials MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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7 AACT Clinical Trials MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.