attach_image_data_to_card
Attach an image to a card from base64 data or data URL (for screenshot uploads)
This record as markdown: /tools/io-github-delorenj-mcp-server-trello/attach-image-data-to-card.md
What attach_image_data_to_card does on Trello
AI agents use attach_image_data_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.
Why attach_image_data_to_card is rated Medium
This tool modifies a Trello card by adding an image attachment to it. The operation is reversible (the attachment can be removed later), and has no external side effects beyond the Trello workspace. It falls clearly into the Write category.
From the tool's definition The tool name is 'attach_image_data_to_card' and the description states it will 'Attach an image to a card from base64 data or data URL', which creates or adds new data (an image attachment) to an existing Trello card. This is a modification operation.
Attacks that exploit this kind of access
The rule that runs attach_image_data_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_image_data_to_card, this is the rule to start with:
attach_image_data_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.
The button opens the PolicyLayer dashboard: create your workspace, connect Trello, apply this rule, and every attach_image_data_to_card call is checked against it from then on.
Questions about attach_image_data_to_card
Attach an image to a card from base64 data or data URL (for screenshot uploads). 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 attach_image_data_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.
attach_image_data_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 attach_image_data_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 attach_image_data_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.
attach_image_data_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.
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