AI agents call get_market_clock 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 fetches read-only market timing information (current status, next open/close times) with no side effects. It cannot modify any data or trigger any operations.
From the tool's definition Retrieves and formats current market status and next open/close times
Attacks that exploit this kind of access
Retrieves and formats current market status and next open/close times. 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_clock: 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_clock 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_clock 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_clock. 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_clock 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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