Tool and LLM retry mechanisms and checkpoints

[reyolivo]

Hello,

As part of building agentic workflows, I was wondering if the ADK core team will add some retry mechanisms and checkpoints to both model and tool invocations? Some issues I face is within multi-agent systems - where there may be an error caught via a callback or plugin, but no reliable way to reroute to an earlier step (or even retry the failed event). Especially in Multi-Agent workflows, this is tough to manage in ADK today.

E.g. we have a Sequential which has 3 subagents (CategorizationAgent, ValidatorAgent, FinalizeAgent)

What if we have a tool hallucination error during the FinalizeAgent (an unknown tool is called), and we wish to just have the FinalizeAgent retry the tool calling process (no current way to do this).

Another problem could be: the error has to do with Agent to Agent handsoffs and the output from one agent causes an input-Pydantic formatting error. Let's say the ValidatorAgent has a validatedOutput, and the FinalizeAgent expects this validatedOutput to have a certain format, but in this case, the formatting is malformed.. .so we'd want to completely retry from a certain event checkpoint in the prior agent (ValidatorAgent) with context on what the error was, to have the LLM generate a properly formatted answer.

The idea of checkpoints could be interesting to add to ADK in general along with retry mechanisms for both Tools and LLMs.

At the moment, I am inclined to rely on another tool to better facilitate such workflow orchestration features, and only relying on ADK for the core agent / LLM logic (limiting my usage of workflow agents in general).

Thanks!

• Rey Olivo

[xuanyang15]

Hi @reyolivo, thanks for starting this conversion! I have something to share for retry mechanisms. We recently added a ReflectAndRetryToolPlugin which can retry tool calls for errors, including hallucinated tool calls. Could you please take a look if it can resolve some of your issues.

Here is a sample agent to demonstrate the usage of the retry plugin: contributing/samples/plugin_reflect_tool_retry.