Low Risk

semantic_search

Search for medical concepts using natural language with neural embeddings. Unlike keyword search, semantic search understands clinical meaning —

Part of the Omophub server.

semantic_search is read-only, but an agent in a loop can still rack up calls and cost. PolicyLayer caps every call before it runs. Live in minutes.

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AI agents call semantic_search to retrieve information from Omophub without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.

Even though semantic_search only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.

Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "semantic_search": {}
  }
}

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These attack patterns abuse exactly the kind of access semantic_search gives an agent. Each links to the full case and the policy that stops it:

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Every attack above starts with a tool call. PolicyLayer checks each one against your policy first, so semantic_search only ever does what you allow.

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Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.

What does the semantic_search tool do? +

Search for medical concepts using natural language with neural embeddings. Unlike keyword search, semantic search understands clinical meaning —. It is categorised as a Read tool in the Omophub MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on semantic_search? +

Register the Omophub MCP server in PolicyLayer and add a rule for 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 Omophub. Nothing to install.

What risk level is semantic_search? +

semantic_search is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit semantic_search? +

Yes. Add a rate_limit block to the 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.

How do I block semantic_search completely? +

Set action: deny in the PolicyLayer policy for 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.

What MCP server provides semantic_search? +

semantic_search is provided by the Omophub MCP server (@omophub/omophub-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Omophub tool call.

Deterministic rules across all 11 Omophub tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.

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4,600+ MCP servers and 31,000+ tools scanned and risk-classified.

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