AI agents invoke connect to trigger actions in Ibmi. 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.
This tool establishes a terminal session to a remote IBM i system. While 'connect' sounds benign, initiating a TN5250 session is an external operation that creates a persistent connection to a production IBM i environment, enabling all subsequent terminal interactions. Misuse could grant unauthorized access to sensitive mainframe-class systems.
From the tool's definition Connect to an IBM i system via TN5250
Documented attack patterns abuse exactly the kind of access connect gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Ibmi, and nothing reaches the server without passing your rules. This is the rule we recommend for connect:
{
"version": "1",
"default": "deny",
"tools": {
"connect": {
"limits": [
{
"counter": "connect_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}connect 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.
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Connect to an IBM i system via TN5250. It is categorised as a Execute tool in the Ibmi MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Ibmi MCP server in PolicyLayer and add a rule for connect: 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 Ibmi. Nothing to install.
connect is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the connect 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.
Set action: deny in the PolicyLayer policy for connect. 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.
connect is provided by the Ibmi MCP server (whitehornltd/ibmi-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Ibmi, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
8 Ibmi tools catalogued and risk-classified — across an index of 43,000+ MCP servers.