Add a shape (rectangle or ellipse) to the topology.
AI agents use gns3_add_shape 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.
This tool creates visual shape objects in the GNS3 topology diagram, which are annotation/drawing artifacts. These are reversible modifications (can be deleted or edited), with no impact on the actual network simulation, device configuration, or traffic. It does not execute network operations, delete data irreversibly, or create side effects beyond topology visualization.
From the tool's definition Tool description states 'Add a shape (rectangle or ellipse) to the topology' — creates new visual elements in the simulation canvas. The verb 'Add' indicates creation of reversible data (drawing/annotation).
Documented attack patterns abuse exactly the kind of access gns3_add_shape 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_shape:
{
"version": "1",
"default": "deny",
"tools": {
"gns3_add_shape": {
"limits": [
{
"counter": "gns3_add_shape_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}gns3_add_shape 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.
Add a shape (rectangle or ellipse) to the topology. 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_shape: 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_shape 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_shape 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_shape. 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_shape 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.