get_card_custom_fields

Get the Custom Field values on a Trello card. Returns every custom field defined on the card

SERVERTrello SOURCE@asapo/trello-mcp-server

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade D, identity unverified Pull the record →

This record as markdown: /tools/asapo-trello-mcp-server/get-card-custom-fields.md

WHAT IT DOES

What get_card_custom_fields does on Trello

AI agents call get_card_custom_fields to retrieve information from Trello without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

RISK

Why get_card_custom_fields is rated Low

Even though get_card_custom_fields only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.

Risk signalsBulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs get_card_custom_fields 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 get_card_custom_fields, this is the rule to start with:

get_card_custom_fields Allowed

get_card_custom_fields is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "get_card_custom_fields": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

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

FAQ

Questions about get_card_custom_fields

What does the get_card_custom_fields tool do? +

Get the Custom Field values on a Trello card. Returns every custom field defined on the card. It is categorised as a Read tool in the Trello MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on get_card_custom_fields? +

Register the Trello MCP server in PolicyLayer and add a rule for get_card_custom_fields: 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 get_card_custom_fields? +

get_card_custom_fields is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit get_card_custom_fields? +

Yes. Add a rate_limit block to the get_card_custom_fields 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 get_card_custom_fields completely? +

Set action: deny in the PolicyLayer policy for get_card_custom_fields. 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 get_card_custom_fields? +

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

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