find_instruments

THE RISK

Low Risk

Why find_instruments needs a policy

This tool retrieves or queries stock market instrument data (symbols, details, specifications) without creating, modifying, deleting, or executing any financial transactions. The verb 'searches' and 'information' clearly denote a read-only operation. While the server provides trading capabilities, this specific tool is purely informational lookup functionality.

From the tool's definition Tool name 'find_instruments' and description 'Searches for instrument information by various criteria' indicate a query/lookup operation with no data modification or execution of trades.

Documented attack patterns abuse exactly the kind of access find_instruments gives an agent:

POLICY

How to control find_instruments

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 find_instruments:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "find_instruments": {}
  }
}

find_instruments is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Open Stocks MCP — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

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All 152 Open Stocks MCP tools →

Read tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about find_instruments

What does the find_instruments tool do? +

Searches for instrument information by various criteria. It is categorised as a Read tool in the Open Stocks MCP MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on find_instruments? +

Register the Open Stocks MCP server in PolicyLayer and add a rule for find_instruments: 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.

What risk level is find_instruments? +

find_instruments is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit find_instruments? +

Yes. Add a rate_limit block to the find_instruments 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.

How do I block find_instruments completely? +

Set action: deny in the PolicyLayer policy for find_instruments. 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.

What MCP server provides find_instruments? +

find_instruments 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.

Enforce policy on every Open Stocks MCP tool call.

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.

CHECK YOUR STACK →