attach_file_to_card

Attach any file to a card from a URL on a specific board

SERVERTrello SOURCE@delorenj/mcp-server-trello

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-delorenj-mcp-server-trello/attach-file-to-card.md

WHAT IT DOES

What attach_file_to_card does on Trello

AI agents use attach_file_to_card 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.

RISK

Why attach_file_to_card is rated Medium

Attaching a file to a card is a data modification action that persists in Trello but can be undone (attachment can be removed). It does not irreversibly destroy data (not Destructive), execute arbitrary code (not Execute), involve financial transactions (not Financial), or merely read data (not Read).

From the tool's definition Tool description states 'Attach any file to a card' which modifies card state by adding an attachment. This is a reversible write operation (attachments can be removed).

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs attach_file_to_card safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Trello, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For attach_file_to_card, this is the rule to start with:

attach_file_to_card Rate-limited

attach_file_to_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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "attach_file_to_card": {
      "limits": [
        {
          "counter": "attach_file_to_card_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Trello, apply this rule, and every attach_file_to_card call is checked against it from then on.

FAQ

Questions about attach_file_to_card

What does the attach_file_to_card tool do? +

Attach any file to a card from a URL on a specific board. 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.

How do I enforce a policy on attach_file_to_card? +

Register the Trello MCP server in PolicyLayer and add a rule for attach_file_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. Nothing to install.

What risk level is attach_file_to_card? +

attach_file_to_card is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit attach_file_to_card? +

Yes. Add a rate_limit block to the attach_file_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.

How do I block attach_file_to_card completely? +

Set action: deny in the PolicyLayer policy for attach_file_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.

What MCP server provides attach_file_to_card? +

attach_file_to_card is provided by the Trello MCP server (@delorenj/mcp-server-trello). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Trello, and thousands of servers like it.

This server

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The MCP Attack Database →

Guides

Govern customer-ops agents →Argument validation →Scoped token →