AI agents call a_semantic_search to retrieve information from Heuristic without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Even though a_semantic_search only reads data, uncontrolled read access leaks sensitive information and racks up API costs — an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
Performs intelligent hybrid code search combining semantic understanding with exact text matching. Ideal for finding code by meaning (e.g.,. It is categorised as a Read tool in the Heuristic MCP Server, which means it retrieves data without modifying state.
Register the Heuristic MCP server in PolicyLayer and add a rule for a_semantic_search: 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 Heuristic. Nothing to install.
a_semantic_search 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 a_semantic_search 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 a_semantic_search. 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.
a_semantic_search is provided by the Heuristic MCP server (softerist/heuristic-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.