AI agents use create_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.
The tool creates a new card, which is a reversible write operation. It does not delete, execute arbitrary code, or move money. While it modifies Trello state, cards can be deleted or archived later. Severity is medium because an AI agent could create many spam/unwanted cards, but the impact is limited to a single board/list and is easily undone.
From the tool's definition Tool name is 'create_card' and description states 'Create a new card in a specific list' — this creates new data in Trello.
Documented attack patterns abuse exactly the kind of access create_card gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Trello MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for create_card:
{
"version": "1",
"default": "deny",
"tools": {
"create_card": {
"limits": [
{
"counter": "create_card_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_card 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.
Free to start. No card required.
Create a new card in a specific list. 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 create_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.
create_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 create_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 create_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.
create_card is provided by the Trello MCP Server MCP server (lzvxck/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 MCP Server, 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.
11 Trello MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.