get_stock_latest_bar
AI agents call get_stock_latest_bar to retrieve information from Alpaca MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves market data (the latest bar/candle for a stock) without modifying any account state, positions, or data. It is a passive data query with no side effects. The severity is low because reading stock price data carries minimal risk—misuse cannot cause financial loss, delete data, or trigger unintended trades.
From the tool's definition The tool name is 'get_stock_latest_bar', which is a getter that retrieves the latest price/OHLC bar data for a stock. The naming convention 'get_' and absence of parameters that would modify data indicate a read-only operation.
Attacks that exploit this kind of access
get_stock_latest_bar. It is categorised as a Read tool in the Alpaca MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Alpaca MCP Server MCP server in PolicyLayer and add a rule for get_stock_latest_bar: 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 Alpaca MCP Server. Nothing to install.
get_stock_latest_bar 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 get_stock_latest_bar 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 get_stock_latest_bar. 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.
get_stock_latest_bar is provided by the Alpaca MCP Server MCP server (metachain-org/alpaca-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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