function Calling cannot generate response

[godguy23]

Hi， I use the fc sdk to test the hammer function calling, when I ask the "What's the weather like today?", it can use the location tool and getWeather tool, but finally, I send the tool result to the Hammer，it response nothing. And when I ask the Hammer “Who are you?”, it response nothing too. The code I write below. Is any code wrong I write ? Thanks a lot for helping me.

[KyoheiG3]

I tried it with the Gemma 3n and after waiting a few minutes I got a response.
Since function calling requires a long response time, if you are using ConstraintOptions.ToolCallOnly, try disabling the constraint on messages after function calling as follows:

val cloned = mChatSession!!.clone()
cloned.disableConstraint()

response = cloned.sendMessage(toolInstruction)

I'm not sure Hammer will work.

[matthewchan-g]

Hi @godguy23,

This behavior is a result of how the Hammer model was trained. If you provide it a system instruction containing tool definitions, it will only respond with tool calls and will output empty string if it doesn't find an appropriate tool. I've also found that it has an empty response when I pass back the function result. You could try a different model (e.g. Gemma 3n) if you need natural language responses.

More details:

The Hammer system instructions are specified by the model authors here: https://huggingface.co/MadeAgents/Hammer2.0-1.5b

The Hammer system instructions are generated by the AI Edge function calling library here:

ai-edge-apis/local_agents/function_calling/core/hammer_formatter.cc

Line 51 in d740e28

constexpr absl::string_view kTasksToolsFormatInstructions =