Subscribe to a list. Use this tool to receive notifications about changes to a list.
AI agents use subscribe_to_list to create or update resources in Trello — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Trello environment.
Subscribing to a list modifies a user's notification/subscription state on Trello, which is a reversible write operation. It doesn't delete data, execute code, or involve financial transactions. The blast radius is low since it only affects notification preferences.
From the tool's definition Subscribe to a list. Use this tool to receive notifications about changes to a list.
Documented attack patterns abuse exactly the kind of access subscribe_to_list gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Trello, and nothing reaches the server without passing your rules. This is the rule we recommend for subscribe_to_list:
{
"version": "1",
"default": "deny",
"tools": {
"subscribe_to_list": {
"limits": [
{
"counter": "subscribe_to_list_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}subscribe_to_list 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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Subscribe to a list. Use this tool to receive notifications about changes to a list. It is categorised as a Write tool in the Trello MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Trello MCP server in PolicyLayer and add a rule for subscribe_to_list: 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 Trello. Nothing to install.
subscribe_to_list 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 subscribe_to_list 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 subscribe_to_list. 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.
subscribe_to_list is provided by the Trello MCP server (v4lheru/trello-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Trello, 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.
76 Trello tools catalogued and risk-classified — across an index of 43,000+ MCP servers.