Search a knowledge base using semantic search via Open WebUI API
AI agents call search_knowledge_base to retrieve information from Open Webui Knowledge without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs semantic search queries against a knowledge base, which is a pure read operation. It retrieves and queries existing data with no side effects, no modifications, no code execution, and no irreversible actions. This clearly fits the Read category with low severity since misuse would only expose information that is presumably already accessible within the user's knowledge base system.
From the tool's definition The tool description explicitly states 'Search a knowledge base using semantic search' and the tool name is 'search_knowledge_base'. The verb 'search' and the context of querying knowledge bases indicate data retrieval without modification.
Documented attack patterns abuse exactly the kind of access search_knowledge_base gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Open Webui Knowledge, and nothing reaches the server without passing your rules. This is the rule we recommend for search_knowledge_base:
{
"version": "1",
"default": "deny",
"tools": {
"search_knowledge_base": {}
}
}search_knowledge_base is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Search a knowledge base using semantic search via Open WebUI API. It is categorised as a Read tool in the Open Webui Knowledge MCP Server, which means it retrieves data without modifying state.
Register the Open Webui Knowledge MCP server in PolicyLayer and add a rule for search_knowledge_base: 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 Open Webui Knowledge. Nothing to install.
search_knowledge_base 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 search_knowledge_base 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 search_knowledge_base. 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.
search_knowledge_base is provided by the Open Webui Knowledge MCP server (ronasit/open-webui-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Open Webui Knowledge, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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3 Open Webui Knowledge tools catalogued and risk-classified — across an index of 43,000+ MCP servers.