modify_order

THE RISK

Critical Risk

Why modify_order needs a policy

Modifying a stock/securities order directly affects financial transactions — it can change price, quantity, or order type on live market orders, committing or altering financial obligations. This falls squarely in the Financial category, which is the most severe.

From the tool's definition 'Modify an existing order' on a trading platform (Fyers) that handles 'order placement' for Indian stock markets

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

POLICY

How to control modify_order

PolicyLayer is an MCP gateway — it sits between your AI agents and Fyers MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for modify_order:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "modify_order": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}

Any call to modify_order is blocked until a human approves it. The rest of the server keeps working.

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

GATE THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Fyers MCP Server tools

Financial place_order place_order Destructive cancel_order Cancel an existing order. Execute authenticate Smart OAuth authentication - opens browser and captures redirect automatically. Read check_auth_status Check current authentication status. Read get_funds Get account funds information. Read get_holdings Get portfolio holdings. Read get_orders Get order history. Read get_positions Get current trading positions.

All 11 Fyers MCP Server tools →

Financial tools on other servers

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Go deeper

Critical-risk tools in Fyers MCP Server → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Human-in-the-loop → When a tool call should wait for a person — and when policy can decide alone.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
How to Add Spending Controls to Any MCP Agent →
Rate Limiting MCP Tool Calls: A Practical Guide →

FAQ

Questions about modify_order

What does the modify_order tool do? +

Modify an existing order. It is categorised as a Financial tool in the Fyers MCP Server MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on modify_order? +

Register the Fyers MCP Server MCP server in PolicyLayer and add a rule for modify_order: 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 Fyers MCP Server. Nothing to install.

What risk level is modify_order? +

modify_order is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit modify_order? +

Yes. Add a rate_limit block to the modify_order 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 modify_order completely? +

Set action: deny in the PolicyLayer policy for modify_order. 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 modify_order? +

modify_order is provided by the Fyers MCP Server MCP server (quantabox/fyers-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Fyers MCP Server tool call.

Start from Fyers MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →