yahoo_stock_history
AI agents call yahoo_stock_history to retrieve information from YFinance MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool appears designed to fetch historical stock information from Yahoo Finance. Despite the empty tool description, the server's stated purpose of providing 'seamless access to Yahoo Finance stock market data' and 'historical data' retrieval, combined with the sibling tools (yahoo_chart, yahoo_quote, yahoo_quote_summary) all being read-only data retrieval functions, strongly indicates this is a Read operation.
From the tool's definition Tool name 'yahoo_stock_history' and server description indicating 'retrieval of real-time quotes, historical data' suggest this retrieves historical stock data without modification.
Attacks that exploit this kind of access
yahoo_stock_history. It is categorised as a Read tool in the YFinance MCP Server MCP Server, which means it retrieves data without modifying state.
Register the YFinance MCP Server MCP server in PolicyLayer and add a rule for yahoo_stock_history: 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 YFinance MCP Server. Nothing to install.
yahoo_stock_history 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 yahoo_stock_history 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 yahoo_stock_history. 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.
yahoo_stock_history is provided by the YFinance MCP Server MCP server (szemeng76/yfinance-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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