Opens Cursor IDE and returns an instance identifier
AI agents invoke open_cursor 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 launches an external application (Cursor IDE), which is an external operation that triggers a side effect beyond simple data retrieval or modification. It executes/spawns a process on the host system, classifying it as Execute. Misuse could result in unwanted application launches or be used as part of a larger attack chain, warranting medium severity.
From the tool's definition Opens Cursor IDE and returns an instance identifier
Documented attack patterns abuse exactly the kind of access open_cursor 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_cursor:
{
"version": "1",
"default": "deny",
"tools": {
"open_cursor": {
"limits": [
{
"counter": "open_cursor_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}open_cursor 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 Cursor IDE and returns an instance identifier. 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_cursor: 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_cursor 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_cursor 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_cursor. 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_cursor 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.