Hybrid search combining full-text and vector similarity (requires pgvector)
AI agents call hybrid_search to retrieve information from Postgres Mcp Legacy without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a search query combining full-text and vector similarity matching. Search and query operations are classified as Read category as they retrieve data without modifying, deleting, or executing external operations. The severity is low because the tool cannot cause data loss or trigger unintended side effects; misuse would only return unexpected search results.
From the tool's definition Tool description states 'Hybrid search combining full-text and vector similarity' — search operations are retrieves/queries with no side effects. No mentions of data modification, deletion, or external operations.
Documented attack patterns abuse exactly the kind of access hybrid_search gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Postgres Mcp Legacy, and nothing reaches the server without passing your rules. This is the rule we recommend for hybrid_search:
{
"version": "1",
"default": "deny",
"tools": {
"hybrid_search": {}
}
}hybrid_search is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Hybrid search combining full-text and vector similarity (requires pgvector). It is categorised as a Read tool in the Postgres Mcp Legacy MCP Server, which means it retrieves data without modifying state.
Register the Postgres Mcp Legacy MCP server in PolicyLayer and add a rule for hybrid_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 Postgres Mcp Legacy. Nothing to install.
hybrid_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 hybrid_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 hybrid_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.
hybrid_search is provided by the Postgres Mcp Legacy MCP server (neverinfamous/postgres-mcp-legacy). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Postgres Mcp Legacy, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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60 Postgres Mcp Legacy tools catalogued and risk-classified — across an index of 43,000+ MCP servers.