Gets Level II order book data for a symbol (requires Gold subscription).
AI agents call pricebook_by_symbol 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 queries Level II order book (market depth) data—a standard read-only market data endpoint. It has no side effects: it does not create orders, modify positions, execute trades, delete data, or move money. The Gold subscription requirement is a licensing/access control detail, not a functional characteristic that elevates the risk category.
From the tool's definition Tool name 'pricebook_by_symbol' and description 'Gets Level II order book data for a symbol' indicate retrieval of market data with no modification or execution of orders.
Documented attack patterns abuse exactly the kind of access pricebook_by_symbol 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 pricebook_by_symbol:
{
"version": "1",
"default": "deny",
"tools": {
"pricebook_by_symbol": {}
}
}pricebook_by_symbol 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.
Gets Level II order book data for a symbol (requires Gold subscription). 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 pricebook_by_symbol: 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.
pricebook_by_symbol 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 pricebook_by_symbol 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 pricebook_by_symbol. 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.
pricebook_by_symbol 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.
Free to start. No card required.
152 Open Stocks MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.