Cancel a subscription by id. Ownership is enforced — you can only cancel your own subscriptions. The row is deactivated (not deleted) so its historical events stay available via recent_alerts.
AI agents use unsubscribe to create or update resources in Expression Atlas — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Expression Atlas environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
id | string | Yes | Subscription id (uuid) returned by subscribe. |
Parameters from the server's own tool schema.
The tool cancels/deactivates a subscription record but explicitly does not delete it, making the action reversible. This fits Write (modifies data reversibly) rather than Destructive. Severity is medium because misuse could cancel legitimate subscriptions, but the data is retained and the scope is limited to the user's own subscriptions.
From the tool's definition 'The row is deactivated (not deleted) so its historical events stay available via recent_alerts' — the operation is reversible (deactivation, not deletion); ownership is enforced limiting blast radius
Attacks that exploit this kind of access
Cancel a subscription by id. Ownership is enforced — you can only cancel your own subscriptions. The row is deactivated (not deleted) so its historical events stay available via recent_alerts. It is categorised as a Write tool in the Expression Atlas MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
unsubscribe accepts 1 parameter: id. Required: id. The full parameter table on this page comes from the server's own tool schema.
Register the Expression Atlas MCP server in PolicyLayer and add a rule for unsubscribe: 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 Expression Atlas. Nothing to install.
unsubscribe 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 unsubscribe 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 unsubscribe. 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.
unsubscribe is provided by the Expression Atlas MCP server (https://gateway.pipeworx.io/expression-atlas/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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