AI agents invoke resume_workflow to trigger actions in Workflows. 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.
The tool name 'resume_workflow' strongly implies continuing/resuming a paused or suspended workflow execution. Given the server's purpose of running YAML workflows to automate real tasks, resuming a workflow triggers execution of potentially arbitrary automated actions. This falls under Execute as it triggers external operations. Severity is high because workflows can automate real tasks with broad blast radius.
From the tool's definition Tool name 'resume_workflow' on a server designed to 'Run YAML workflows as MCP tools so agents can automate real tasks'. Sibling tools include 'execute_workflow' and 'execute_inline_workflow', indicating workflow execution context.
Documented attack patterns abuse exactly the kind of access resume_workflow gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Workflows, and nothing reaches the server without passing your rules. This is the rule we recommend for resume_workflow:
{
"version": "1",
"default": "deny",
"tools": {
"resume_workflow": {
"limits": [
{
"counter": "resume_workflow_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}resume_workflow 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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resume_workflow. It is categorised as a Execute tool in the Workflows MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Workflows MCP server in PolicyLayer and add a rule for resume_workflow: 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 Workflows. Nothing to install.
resume_workflow 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 resume_workflow 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_workflow. 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_workflow is provided by the Workflows MCP server (qtsone/workflows-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Workflows, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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13 Workflows tools catalogued and risk-classified — across an index of 43,000+ MCP servers.