AI agents call get_market_calendar to retrieve information from Alpaca without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only queries and returns calendar information with no side effects. It retrieves publicly available market data without creating, modifying, deleting, or executing any actions. Despite being on a financial trading server, the tool itself is purely informational and read-only.
From the tool's definition Tool name and description indicate retrieval of market calendar data: 'Retrieves and formats market calendar for specified date range.' No mutations, deletions, or external operations are performed.
Attacks that exploit this kind of access
Retrieves and formats market calendar for specified date range. It is categorised as a Read tool in the Alpaca MCP Server, which means it retrieves data without modifying state.
Register the Alpaca MCP server in PolicyLayer and add a rule for get_market_calendar: 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. Nothing to install.
get_market_calendar 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_market_calendar 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_market_calendar. 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_market_calendar is provided by the Alpaca MCP server (mfoster5303-1/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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