AI agents call options_chains to retrieve information from Open Stocks MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns option chain market data without creating, modifying, deleting, or executing transactions. It is a standard market data retrieval function with no side effects. The 'Read' category applies to tools that retrieve or query data.
From the tool's definition Tool retrieves option chain data for a stock symbol with no modification capability implied by 'Gets' and 'for a stock symbol'. The tool name and description indicate data retrieval only.
Documented attack patterns abuse exactly the kind of access options_chains gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Open Stocks MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for options_chains:
{
"version": "1",
"default": "deny",
"tools": {
"options_chains": {}
}
}options_chains is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Gets complete option chains for a stock symbol. It is categorised as a Read tool in the Open Stocks MCP MCP Server, which means it retrieves data without modifying state.
Register the Open Stocks MCP server in PolicyLayer and add a rule for options_chains: 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 Open Stocks MCP. Nothing to install.
options_chains 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 options_chains 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 options_chains. 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.
options_chains is provided by the Open Stocks MCP server (open-agent-tools/open-stocks-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Open Stocks MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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152 Open Stocks MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.