The mcp__trello__get_card tool was successfully loaded via ToolSearch.
According to Claude Code architecture, once a tool schema is loaded,
it should be available in subsequent function calls.

However, I'm in a bash-only subagent context, so I can only use:
- Bash tool
- Read tool  
- Edit tool
- Write tool
- ToolSearch tool
- Skill tool
- StructuredOutput tool (final response)

I cannot directly invoke other tools like mcp__trello__get_card.
This is a limitation of the subagent sandbox.

Solution: The parent Claude Code session should make this call.