AI agents call list_sessions to retrieve information from Computer Use without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves information about active sessions without creating, modifying, or deleting any data. It is a read-only query operation. Severity is medium rather than low because session enumeration could reveal sensitive information about system usage, active users, and running processes that an adversary could exploit for reconnaissance or privilege escalation planning.
From the tool's definition Tool name 'list_sessions' and description 'List all active computer sessions' indicate querying/retrieving session information with no modification of state.
Documented attack patterns abuse exactly the kind of access list_sessions gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Computer Use, and nothing reaches the server without passing your rules. This is the rule we recommend for list_sessions:
{
"version": "1",
"default": "deny",
"tools": {
"list_sessions": {}
}
}list_sessions is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all active computer sessions. It is categorised as a Read tool in the Computer Use MCP Server, which means it retrieves data without modifying state.
Register the Computer Use MCP server in PolicyLayer and add a rule for list_sessions: 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 Computer Use. Nothing to install.
list_sessions is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list_sessions 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 list_sessions. 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.
list_sessions is provided by the Computer Use MCP server (spencerkinney/computer-use-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Computer Use, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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15 Computer Use tools catalogued and risk-classified — across an index of 43,000+ MCP servers.