View an Action’s Unique Apex Name

For example, if your API spec defines a response accountDetails for a getAccount operation, referenced in the spec as

"paths": {
        "/accounts/{accountName}": {
            "get": {
                "operationId": "getAccount",
                "summary": "Retrieves an account",
                "description": "Retrieves the account with specific name",
                "consumes": [
                    "text/plain"
                ],
                "produces": [
                    "application/json"
                ],
                "parameters": [
                    {
                        "name": "accountName",
                        "in": "path",
                        "required": true,
                        "type": "string",
                        "description": "Name of the account"
                    }
                ],
                "responses": {
                    "200": {
                        "description": "The response when system finds an account with given name",
                        "schema": {
                            "$ref": "#/definitions/accountDetails"
                        }

Where the definition for accountDetails is defined at the end of the spec as

"definitions": {
        "accountDetails": {
            "required": [
                "id",
                "name",
                "type",
                "availableBal"
            ],
            "properties": {
                "id": {
                    "type": "string",
                    "description": "id"
                },
                "name": {
                    "type": "string",
                    "description": "name"
                },
                "type": {
                    "type": "string",
                    "description": "type"
                },
                "availableBal": {
                    "type": "string",
                    "description": "availableBal"
                }
            }
        },

When the spec is registered in External Services, you can see the Apex Class name during registration.

Or you can navigate to the action in External Services and then click View Actions > More Details.

External Services automatically registered our accountDetails object as BankService_accountDetails.

Now in Flow, when you add a resource for a new action, it’s clear that you’re selecting the correct action from the correct registration.