AI agents call list_brains to retrieve information from TheBrain MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a straightforward listing/query operation that retrieves information about user resources. It performs no data modification, deletion, or external operation execution. The blast radius of misuse is minimal—an agent could enumerate available brains but cannot alter them or cause harm through this tool alone.
From the tool's definition Tool name 'list_brains' and description 'List all available brains for the user' indicate a retrieval operation that queries available knowledge bases without modification or side effects.
Documented attack patterns abuse exactly the kind of access list_brains gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and TheBrain MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_brains:
{
"version": "1",
"default": "deny",
"tools": {
"list_brains": {}
}
}list_brains is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
List all available brains for the user. It is categorised as a Read tool in the TheBrain MCP Server MCP Server, which means it retrieves data without modifying state.
Register the TheBrain MCP Server MCP server in PolicyLayer and add a rule for list_brains: 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 TheBrain MCP Server. Nothing to install.
list_brains 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 list_brains 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 list_brains. 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.
list_brains is provided by the TheBrain MCP Server MCP server (redmorestudio/thebrain-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from TheBrain MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
26 TheBrain MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.