legacy GA
Custom Agents
Custom Agents is legacy, replaced by Agent Bricks CLI (legacy since October 2026).
Mosaic AI Agent Framework Custom Agents Agent Bricks CLI
The original code-first brick in Agent Bricks - author an agent in Python with whatever library you like, wrap it in an MLflow ResponsesAgent, and deploy it as a Databricks App with the MLflow AgentServer or to Model Serving.
- The rename was announced in a blog post and nowhere else. No release note on any cloud says the words, and the docs were simply find-and-replaced under it.
- Your agent only shows up in the workspace Agents list if you named the app with an agent- prefix, so the product is opt-in at the level of a string.
- Its Model Serving path spent months telling you to move to Databricks Apps, and then in October 2026 the Apps path it recommended was filed under Legacy too.
Limitations: Deploying on Databricks Apps supports only medium and large compute sizes, and the MLflow Review App Chat UI does not currently support agents deployed on Databricks Apps (use labeling sessions to evaluate existing traces instead).
Open in REbricked →- Category
- AI / ML
- Also known as
- Agent Bricks Custom Agents, Custom Agents on Apps, custom code agents
- Verified
- 2026-10-14
Sources
- Official Official Databricks / Microsoft docs
- Official Databricks docs: Legacy agent offerings
- Official Databricks release notes: Agent Bricks documentation for code-first agent development, with a Legacy section (October 5, 2026)
- Official Databricks docs: Agent Runtime (where new code agents deploy)
- Official Databricks blog: Custom Agents now available on Databricks (February 2026)