MCP Server: Tools Not Registered Unless startingInputTypes Is Explicitly Specified

[BuntyRaghani]

While creating an MCP server using Embabel, tools are not being registered unless the startingInputTypes attribute is explicitly provided in the @export annotation.

Emababel Agent Version: 0.3.0-SNAPSHOT

Steps to Reproduce:

1. Remove startingInputTypes — the tool is not registered.
2. Set startingInputTypes = {} — the tool is still not registered.
3. Set startingInputTypes = {String.class} (even though the method requires no input) — the tool gets registered, but Claude Desktop fails to enable the MCP server.

Expected Behavior:
Tools should register even when startingInputTypes is not specified, especially when the action method does not accept any input parameters.
(Please correct me if my understanding is incorrect.)

Sample Code:

import com.embabel.agent.api.annotation.AchievesGoal;
import com.embabel.agent.api.annotation.Action;
import com.embabel.agent.api.annotation.Agent;
import com.embabel.agent.api.annotation.Export;
import com.embabel.agent.domain.io.UserInput;

@Agent(description = "Test Agent")
public class TestAgent {

    @Action
    @AchievesGoal(description = "Greet User",
            export = @Export(remote = true, name = "greetUser", startingInputTypes = {UserInput.class})
    )
    public String greetUser() {
        return "Hello";
    }
}

[johnsonr]

This is intended behaviour. Is it valid for a tool not to take input types?
Open to discussion.