mcp_server_run_tool

Invoke a tool on a downstream MCP server through the gateway. Risk 3.

SERVERLocalAnt SOURCEyuga-hashimoto/localant

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/yuga-hashimoto-localant/mcp-server-run-tool.md

WHAT IT DOES

What mcp_server_run_tool does on LocalAnt

AI agents invoke mcp_server_run_tool to trigger actions in LocalAnt. 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 mcp_server_run_tool is rated High

This tool allows invoking any tool on downstream MCP servers, effectively bypassing the gateway's approval/permissioning model by delegating to unvetted downstream tools. An AI agent misusing this could trigger destructive, financial, or arbitrary code execution on connected systems. The critical severity reflects the gateway's loss of control over what actually executes on the target servers.

From the tool's definition Tool name 'mcp_server_run_tool' with description 'Invoke a tool on a downstream MCP server through the gateway' indicates execution of arbitrary tools on remote servers. The note 'Risk 3' (highest risk category) confirms this is a dangerous capability.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs mcp_server_run_tool safely

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

mcp_server_run_tool Rate-limited

mcp_server_run_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": {
    "mcp_server_run_tool": {
      "limits": [
        {
          "counter": "mcp_server_run_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 LocalAnt, apply this rule, and every mcp_server_run_tool call is checked against it from then on.

FAQ

Questions about mcp_server_run_tool

What does the mcp_server_run_tool tool do? +

Invoke a tool on a downstream MCP server through the gateway. Risk 3. It is categorised as a Execute tool in the LocalAnt MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on mcp_server_run_tool? +

Register the LocalAnt MCP server in PolicyLayer and add a rule for mcp_server_run_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 LocalAnt. Nothing to install.

What risk level is mcp_server_run_tool? +

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

Can I rate-limit mcp_server_run_tool? +

Yes. Add a rate_limit block to the mcp_server_run_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 mcp_server_run_tool completely? +

Set action: deny in the PolicyLayer policy for mcp_server_run_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 mcp_server_run_tool? +

mcp_server_run_tool is provided by the LocalAnt MCP server (yuga-hashimoto/localant). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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