Resize the terminal dimensions of a session. The TUI app will receive a SIGWINCH signal.
AI agents invoke resize to trigger actions in Tui. 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.
Resizing a terminal session sends a SIGWINCH signal to the running process, which is an external operation that triggers signal delivery to a process. This goes beyond a simple read or write — it actively interacts with a running process via OS signals. Misuse could disrupt TUI applications or cause unexpected behavior in signal handlers.
From the tool's definition Resize the terminal dimensions of a session. The TUI app will receive a SIGWINCH signal.
Documented attack patterns abuse exactly the kind of access resize gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Tui, and nothing reaches the server without passing your rules. This is the rule we recommend for resize:
{
"version": "1",
"default": "deny",
"tools": {
"resize": {
"limits": [
{
"counter": "resize_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}resize 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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Resize the terminal dimensions of a session. The TUI app will receive a SIGWINCH signal. It is categorised as a Execute tool in the Tui MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Tui MCP server in PolicyLayer and add a rule for resize: 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 Tui. Nothing to install.
resize 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 resize 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 resize. 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.
resize is provided by the Tui MCP server (nvms/tui-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Tui, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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13 Tui tools catalogued and risk-classified — across an index of 43,000+ MCP servers.