add_custom_rule

THE RISK

Medium Risk

Why add_custom_rule needs a policy

This tool creates new custom rules in the tech debt analysis system, which modifies stored configuration state reversibly. It is not destructive (rules can be removed or overwritten), does not execute external code directly (the rule itself may later be executed by 'execute_custom_rules', but this tool only stores the rule definition), and does not involve financial or read-only operations.

From the tool's definition Tool name 'add_custom_rule' and description 'Add a custom pattern-based tech debt rule' indicate creation of new configuration/rule data.

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

POLICY

How to control add_custom_rule

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

policy.json

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

add_custom_rule 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 Tech Debt 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 Tech Debt MCP Server tools

Destructive remove_custom_rule Remove a custom rule by ID. Execute execute_custom_rules Execute all custom rules against code or a file. Read analyze_file Analyze a single file for technical debt issues. Read analyze_project Analyze an entire project for technical debt. Scans all supported files and returns a comp Read check_dependencies Analyze project dependencies across multiple package managers. Read get_debt_summary Get a quick summary of technical debt in a project. Read get_issues_by_category Get all issues of a specific category. Read get_issues_by_severity Get all issues of a specific severity level.

All 16 Tech Debt 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_custom_rule

What does the add_custom_rule tool do? +

Add a custom pattern-based tech debt rule. It is categorised as a Write tool in the Tech Debt 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_custom_rule? +

Register the Tech Debt MCP Server MCP server in PolicyLayer and add a rule for add_custom_rule: 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 Tech Debt MCP Server. Nothing to install.

What risk level is add_custom_rule? +

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

Can I rate-limit add_custom_rule? +

Yes. Add a rate_limit block to the add_custom_rule 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_custom_rule completely? +

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

add_custom_rule is provided by the Tech Debt MCP Server MCP server (pierrejanineh/techdebtmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Tech Debt MCP Server tool call.

Start from Tech Debt 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 →