Lists all registered brokers and their availability.
AI agents call list_brokers to retrieve information from Open Stocks MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and displays information about available brokers without creating, modifying, deleting, or executing any operations. It is a purely informational read operation with minimal blast radius if misused—an AI agent cannot cause harm by listing brokers. The low severity reflects that this is passive data retrieval.
From the tool's definition Tool name 'list_brokers' and description 'Lists all registered brokers and their availability' indicate a query/retrieval operation with no data modification or execution.
Documented attack patterns abuse exactly the kind of access list_brokers gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Open Stocks MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for list_brokers:
{
"version": "1",
"default": "deny",
"tools": {
"list_brokers": {}
}
}list_brokers is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Lists all registered brokers and their availability. It is categorised as a Read tool in the Open Stocks MCP MCP Server, which means it retrieves data without modifying state.
Register the Open Stocks MCP server in PolicyLayer and add a rule for list_brokers: 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 Stocks MCP. Nothing to install.
list_brokers 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_brokers 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_brokers. 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_brokers is provided by the Open Stocks MCP server (open-agent-tools/open-stocks-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Open Stocks MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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152 Open Stocks MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.