AI agents use create_webhook_subscription to create or update resources in Mycase — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mycase environment.
Webhook subscriptions are reversible configurations that create new monitoring triggers in the system without deleting or overwriting existing data. This is a Write operation rather than Read (it creates, not retrieves), Execute (it doesn't run external code directly—it configures event handlers), or Destructive (it can be deleted/unsubscribed).
From the tool's definition Tool description states 'Create a webhook' — a webhook subscription creation is a Write operation that establishes a new data structure (the subscription record) in the MyCase system.
Attacks that exploit this kind of access
Create a webhook. model: resource type (case|client|company|event|lead|message). actions: comma-separated list of created|updated|deleted (e.g. 'created,updated'). It is categorised as a Write tool in the Mycase MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Mycase MCP server in PolicyLayer and add a rule for create_webhook_subscription: 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 Mycase. Nothing to install.
create_webhook_subscription 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_webhook_subscription 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_webhook_subscription. 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_webhook_subscription is provided by the Mycase MCP server (rosenadvertising/mycase-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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