Add a label to a card.
AI agents use add_label_to_card to create or update resources in Trello MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Trello MCP Server environment.
An AI agent can call add_label_to_card faster than any human can review — one bad instruction and it creates or modifies resources in Trello MCP Server by the hundred, each call as confident as the last.
Attacks that exploit this kind of access
Add a label to a card. It is categorised as a Write tool in the Trello MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Trello MCP Server MCP server in PolicyLayer and add a rule for add_label_to_card: 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 MCP Server. Nothing to install.
add_label_to_card 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 add_label_to_card 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 add_label_to_card. 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.
add_label_to_card is provided by the Trello MCP Server MCP server (pypi:fastmcp-trello). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.