Hello,

I am currently integrating Gemma 4 (via vLLM) with Hermes Agent and encountering issues with tool calling parsing.

Context

Setup:

• Model: google/gemma-4-E4B-it

• Runtime: vLLM (vllm-openai:gemma4)

• Flags:

  • --tool-call-parser gemma4
  • --enable-auto-tool-choice

• Hermes Agent (latest version)

Observed behavior

Gemma 4 produces tool calls in the following format:

<|tool_call>call:search_files{pattern:<|"|>/var/log<|"|>,target:<|"|>files<|"|>}<tool_call|>

However:

• The tool_calls field is empty
• The tool call remains embedded in message.content
• Hermes does not execute the tool, as it relies on message.tool_calls

This results in a silent failure of tool execution.

This behavior appears consistent with other reports where:

• Gemma outputs valid tool calls
• but parsers fail to extract them into structured fields ([GitHub]1)

Questions

1. Does Hermes Agent currently support a native Gemma parser?

   • I could not find any gemma parser in environments/tool_call_parsers
   • Is this planned or already available under another name?

2. Is there a recommended parser for Gemma 4?

   • pythonic seems partially compatible with call:func{...} formats
   • but Gemma 4 uses <|tool_call> ... <tool_call|> tokens

3. Is a custom chat_template required for Gemma?

   • vLLM documentation suggests that only some models have built-in tool templates
   • Gemma appears to require explicit formatting ([vLLM]2)

4. Is Hermes expected to handle raw tool call text as fallback?

   • Currently Hermes only checks message.tool_calls
   • Would a fallback parsing mechanism (from content) be considered?

Goal

Clarify the recommended way to use Gemma 4 + vLLM with Hermes, and whether first-class support is planned.

Thanks!