run_custom_tool

Execute a custom tool defined in project configuration

SERVERCode MCP Server SOURCEagentics-ai/code-mcp

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/agentics-ai-code-mcp/run-custom-tool.md

WHAT IT DOES

What run_custom_tool does on Code MCP Server

AI agents invoke run_custom_tool to trigger actions in Code MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

RISK

Why run_custom_tool is rated High

This tool triggers execution of arbitrary custom tools as defined in project configuration files. While the execution is constrained to project-defined tools (mitigating factor), the actual effects are unpredictable and depend on what those custom tools do—they could read, write, delete data, or trigger external operations.

From the tool's definition Tool description states 'Execute a custom tool defined in project configuration' and server description mentions 'secure command execution using project-specific configurations.' The verb 'Execute' directly indicates code/command execution whose effects…

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs run_custom_tool safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Code MCP Server, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For run_custom_tool, this is the rule to start with:

run_custom_tool Rate-limited

run_custom_tool stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "run_custom_tool": {
      "limits": [
        {
          "counter": "run_custom_tool_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Code MCP Server, apply this rule, and every run_custom_tool call is checked against it from then on.

FAQ

Questions about run_custom_tool

What does the run_custom_tool tool do? +

Execute a custom tool defined in project configuration. It is categorised as a Execute tool in the Code MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on run_custom_tool? +

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

What risk level is run_custom_tool? +

run_custom_tool is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit run_custom_tool? +

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

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

run_custom_tool is provided by the Code MCP Server MCP server (agentics-ai/code-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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