yfinance_get_price_history
AI agents call yfinance_get_price_history to retrieve information from Yahoo Finance 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 historical price information from Yahoo Finance. Price history queries are read-only operations that retrieve existing data without modifying, deleting, or executing external operations. The blast radius of misuse is minimal—an agent could only fetch data it shouldn't have access to, not cause financial transactions or data loss.
From the tool's definition Tool name 'yfinance_get_price_history' indicates retrieval of historical price data. The server description states it 'provides a set of tools to fetch stock data' with no mention of modification or execution capabilities.
Attacks that exploit this kind of access
yfinance_get_price_history. It is categorised as a Read tool in the Yahoo Finance MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Yahoo Finance MCP Server MCP server in PolicyLayer and add a rule for yfinance_get_price_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 Yahoo Finance MCP Server. Nothing to install.
yfinance_get_price_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 yfinance_get_price_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 yfinance_get_price_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.
yfinance_get_price_history is provided by the Yahoo Finance MCP Server MCP server (narumiruna/yfinance-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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