Save current CMUX state (workspaces, panes, CLIs, session IDs) to a manifest for crash recovery. Call this after launching agents or making changes you want to be recoverable.
AI agents use cmux_session_save to create or update resources in Cmux Agent — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Cmux Agent environment.
The tool persists application state to a manifest file for recovery purposes. This is a write operation that creates or modifies data (the manifest) reversibly. While the tool itself is not destructive, it modifies persistent state. It does not execute arbitrary commands, does not delete data irreversibly, and does not move money.
From the tool's definition Save current CMUX state (workspaces, panes, CLIs, session IDs) to a manifest for crash recovery. Call this after launching agents or making changes you want to be recoverable.
Documented attack patterns abuse exactly the kind of access cmux_session_save gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Cmux Agent, and nothing reaches the server without passing your rules. This is the rule we recommend for cmux_session_save:
{
"version": "1",
"default": "deny",
"tools": {
"cmux_session_save": {
"limits": [
{
"counter": "cmux_session_save_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}cmux_session_save stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Save current CMUX state (workspaces, panes, CLIs, session IDs) to a manifest for crash recovery. Call this after launching agents or making changes you want to be recoverable. It is categorised as a Write tool in the Cmux Agent MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Cmux Agent MCP server in PolicyLayer and add a rule for cmux_session_save: 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 Cmux Agent. Nothing to install.
cmux_session_save is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the cmux_session_save 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 cmux_session_save. 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.
cmux_session_save is provided by the Cmux Agent MCP server (multiagentcognition/cmux-agent-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Cmux Agent, 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.
63 Cmux Agent tools catalogued and risk-classified — across an index of 43,000+ MCP servers.