add_test_script

THE RISK

Medium Risk

Why add_test_script needs a policy

This tool adds scripts to Bruno API requests, which modifies existing request configurations. While it writes/modifies data, the changes are to test scripts in a local API collection (reversible). However, scripts could contain executable logic — but the tool itself is a write operation that attaches scripts rather than executing them.

From the tool's definition Add pre-request or post-response scripts to Bruno requests

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

POLICY

How to control add_test_script

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "add_test_script": {
      "limits": [
        {
          "counter": "add_test_script_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

add_test_script stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

Create a free account and register Bruno 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.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Bruno MCP Server tools

Write create_collection Create a new Bruno API testing collection with configuration Write create_crud_requests Generate a complete set of CRUD operations for an entity Write create_environment Create environment configuration files for Bruno collection Write create_request Generate .bru request files for API testing Write create_test_suite Generate comprehensive test collections with multiple related requests Read get_collection_stats Get detailed statistics about a Bruno collection Read list_collections List all Bruno collections in a directory

All 8 Bruno MCP Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about add_test_script

What does the add_test_script tool do? +

Add pre-request or post-response scripts to Bruno requests. It is categorised as a Write tool in the Bruno MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_test_script? +

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

What risk level is add_test_script? +

add_test_script is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit add_test_script? +

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

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

add_test_script is provided by the Bruno MCP Server MCP server (macarthy/bruno-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Bruno MCP Server tool call.

Start from Bruno 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 →