AI agents call search_with_regex to retrieve information from MCP Long Context Reader without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Despite having an empty description, the tool name 'search_with_regex' combined with the server's stated purpose of enabling LLM agents to read and query documents clearly indicates this is a read-only operation that retrieves data matching a regex pattern. Regex search cannot modify, delete, or execute arbitrary code—it only returns matches.
From the tool's definition Tool name is 'search_with_regex' and server description indicates this toolkit is designed to 'read' and query long documents. The tool name contains 'search', which is a read operation that retrieves matching content from documents.
Documented attack patterns abuse exactly the kind of access search_with_regex gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Long Context Reader, and nothing reaches the server without passing your rules. This is the rule we recommend for search_with_regex:
{
"version": "1",
"default": "deny",
"tools": {
"search_with_regex": {}
}
}search_with_regex is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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search_with_regex. It is categorised as a Read tool in the MCP Long Context Reader MCP Server, which means it retrieves data without modifying state.
Register the MCP Long Context Reader MCP server in PolicyLayer and add a rule for search_with_regex: 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 MCP Long Context Reader. Nothing to install.
search_with_regex 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_with_regex 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_with_regex. 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_with_regex is provided by the MCP Long Context Reader MCP server (yuplin2333/mcp-long-context-reader). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Long Context Reader, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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5 MCP Long Context Reader tools catalogued and risk-classified — across an index of 43,000+ MCP servers.