If you want to add a custom tool for your agent to use, you can use the “add custom tool” in the agent block and just define the JSON schema and the code for the tool call.
If you want a custom integration, you can either request it, or if you are running locally we have really thorough instructions on how you can add a tool/block in the contributing guide for the repo. You can use this to extend the platform for yourself or add integrations to the main repo. Hope that helps!