Elasticsearch Agent Builder Hackathon

Issues with Elastic Agent Builder Affecting Submitted Elastiviz Project

Hi team, I need to report two issues with Elastic Agent Builder that are affecting my already‑submitted hackathon project, Elastiviz.

Project links:
GitHub: https://github.com/YashArote/elastiviz
Devpost: https://devpost.com/software/elastiviz
Everything previously worked correctly, but after recreating the agent on a new Elastic Cloud trial account, the LLM behaviour changed in a way that breaks the project.

Issue 1 — JSON‑Only Enforcement Broken on Claude Sonnet 4.5
The Elastiviz agent relies on strict JSON‑only responses because the backend parser expects structured output.
On my previous trial account, Claude Sonnet 4.5 always responded with valid JSON using the same system prompt and tool schema.
After switching to a new Elastic Cloud trial account:

The same system prompt is used
The same configurations and MCP tools are used
No changes in logic or schema

But now:

Claude Sonnet 4.5 no longer follows the JSON‑only instruction
It responds with natural language instead of structured JSON
This breaks the integration because the response cannot be parsed

This appears to be a model‑level inconsistency that I cannot override.

Issue 2 — Cannot Assign a Different LLM Connector to the Agent
To work around the JSON issue, I created a Google AI Studio connector (Gemini 2.5 Flash):

Created successfully
Connection test passes
Visible in Kibana under connectors

However:

The connector does not appear as an option when editing the agent
There is no UI method to switch the LLM for an existing agent
Unclear whether this is a limitation of the trial tier, Kibana version, or configuration

This leaves the agent locked to the default Sonnet connector, preventing any workaround.

Goal
I need one of the following to ensure the submitted project runs correctly during evaluation:

Restore JSON‑only response compliance for Claude Sonnet 4.5
(as it worked on the previous account)

or

Allow the agent to use the Gemini 2.5 Flash connector instead of being locked to the default model.

Accounts
Elastic Cloud trial account with issues: yasharotetest@gmail.com
Primary contact: yasharote28@gmail.com
I would appreciate any guidance, as the project may fail during evaluation if the agent continues returning non‑JSON responses.