List all supported stock market indices.
AI agents call list_indices to retrieve information from Marketstack 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 and lists financial market index information without side effects. It performs a simple data query operation that returns reference data about available indices. No financial transactions, code execution, data modification, or destructive operations are involved. The blast radius of misuse is minimal—an agent can only retrieve informational data about market indices.
From the tool's definition Tool name 'list_indices' and description 'List all supported stock market indices' indicate a retrieval/query operation with no data modification or execution of external operations.
Attacks that exploit this kind of access
List all supported stock market indices. It is categorised as a Read tool in the Marketstack MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Marketstack MCP Server MCP server in PolicyLayer and add a rule for list_indices: 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 Marketstack MCP Server. Nothing to install.
list_indices 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 list_indices 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 list_indices. 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.
list_indices is provided by the Marketstack MCP Server MCP server (matteoantoci/mcp-marketstack). 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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