How to find parameter when use agent call workflow?

Hi, I need some suggestion about workflow. I build agents. then agent will call workflow and workflow will call webhook in n8n. but i cant know where is the parameter name from agent to workflow. As I know.

Our main workflow
chat on agent> when meet condition> agent call workflow > workflow send data to n8n > n8n > n8n do…something

My problem
I can’t found parameter when result of chat was sent via workflow.

Our step.

  1. agent will return text message and call workflow,
  2. workflow have input field (which i dont know what parameter to use.),
  3. workflow call api as parameter in input field.,

So anyone, can you suggest where to learn about parameter or document when agent call workflow? Best regard