AI agents use gns3_add_node to create or update resources in GNS3 Network Simulator MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your GNS3 Network Simulator MCP Server environment.
Adding a node creates new simulation entities and modifies the network topology in a reversible manner (nodes can be deleted). This is a Write operation. Severity is medium because misuse could create unnecessary simulation complexity or resource consumption, but the impact is confined to a local simulation environment and fully reversible.
From the tool's definition Tool name 'gns3_add_node' combined with context indicating 'creating projects, building network topologies, managing devices' suggests this tool adds (creates) nodes to a GNS3 simulation. The description is empty, limiting specificity.
Documented attack patterns abuse exactly the kind of access gns3_add_node gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and GNS3 Network Simulator MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for gns3_add_node:
{
"version": "1",
"default": "deny",
"tools": {
"gns3_add_node": {
"limits": [
{
"counter": "gns3_add_node_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}gns3_add_node 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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gns3_add_node. It is categorised as a Write tool in the GNS3 Network Simulator MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the GNS3 Network Simulator MCP Server MCP server in PolicyLayer and add a rule for gns3_add_node: 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 GNS3 Network Simulator MCP Server. Nothing to install.
gns3_add_node 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 gns3_add_node 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 gns3_add_node. 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.
gns3_add_node is provided by the GNS3 Network Simulator MCP Server MCP server (wael-rd/gns3-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from GNS3 Network Simulator 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.
42 GNS3 Network Simulator MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.