Opens a new Cline tab in a specific Cursor instance
AI agents invoke open_cline_tab to trigger actions in Cursor 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.
This tool triggers an external operation in the Cursor editor — opening a new tab in a specific instance. While it doesn't delete data or move money, it executes an action in an external application (Cursor IDE) whose effect depends on the target instance argument. It is more than a read or write, as it actively manipulates the editor UI state.
From the tool's definition Opens a new Cline tab in a specific Cursor instance
Documented attack patterns abuse exactly the kind of access open_cline_tab gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Cursor MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for open_cline_tab:
{
"version": "1",
"default": "deny",
"tools": {
"open_cline_tab": {
"limits": [
{
"counter": "open_cline_tab_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}open_cline_tab 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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Opens a new Cline tab in a specific Cursor instance. It is categorised as a Execute tool in the Cursor MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Cursor MCP Server MCP server in PolicyLayer and add a rule for open_cline_tab: 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 Cursor MCP Server. Nothing to install.
open_cline_tab 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 open_cline_tab 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 open_cline_tab. 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.
open_cline_tab is provided by the Cursor MCP Server MCP server (johnneerdael/multiplatform-cursor-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Cursor MCP Server, 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.
3 Cursor MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.