AI agents use create_custom_application to create or update resources in Fortimanager — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Fortimanager environment.
Creating custom applications in FortiManager is a Write operation—it creates or modifies security policy data reversibly. However, severity is elevated to 'high' rather than 'medium' because misuse could allow an AI agent to define malicious applications or bypass application controls, affecting network security posture across managed devices.
From the tool's definition Tool name 'create_custom_application' indicates creation of a new application definition in FortiManager. The description is empty, but the name and context (FortiManager security policy management) strongly suggest this modifies security configurations.
Documented attack patterns abuse exactly the kind of access create_custom_application gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Fortimanager, and nothing reaches the server without passing your rules. This is the rule we recommend for create_custom_application:
{
"version": "1",
"default": "deny",
"tools": {
"create_custom_application": {
"limits": [
{
"counter": "create_custom_application_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_custom_application 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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create_custom_application. It is categorised as a Write tool in the Fortimanager MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Fortimanager MCP server in PolicyLayer and add a rule for create_custom_application: 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 Fortimanager. Nothing to install.
create_custom_application 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 create_custom_application 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 create_custom_application. 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.
create_custom_application is provided by the Fortimanager MCP server (jmpijll/fortimanager-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Fortimanager, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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584 Fortimanager tools catalogued and risk-classified — across an index of 43,000+ MCP servers.