Resume the most recent archived chat session, restoring its messages to the display
AI agents use resume to create or update resources in Mup — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mup environment.
The tool restores archived chat session messages to the active display, which constitutes a reversible modification of the UI state. This is a Write operation (modifies display/session state) rather than a Read operation because it actively restores/loads data into the current session, not merely retrieving it for inspection.
From the tool's definition Tool name 'resume' and description states it 'restoring its messages to the display' — this modifies the current display state by loading and presenting previously archived chat content.
Documented attack patterns abuse exactly the kind of access resume gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mup, and nothing reaches the server without passing your rules. This is the rule we recommend for resume:
{
"version": "1",
"default": "deny",
"tools": {
"resume": {
"limits": [
{
"counter": "resume_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}resume 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.
Free to start. No card required.
Resume the most recent archived chat session, restoring its messages to the display. It is categorised as a Write tool in the Mup MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Mup MCP server in PolicyLayer and add a rule for resume: 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 Mup. Nothing to install.
resume 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 resume 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 resume. 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.
resume is provided by the Mup MCP server (mup-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Mup, 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.
6 Mup tools catalogued and risk-classified — across an index of 43,000+ MCP servers.