Make externalToolDefinitions and externalToolDispatcher available on SessionConfig #411
Description
I'm working on a feature using the SDK where I would like to register my own tools and handle their execution externally (e.g. forwarding tool calls to another piece of software and returning the results back).
While digging into the SDK, I noticed that the SessionOptions in the SDK already has externalToolDefinitions and externalToolDispatcher fields that seem to do exactly this, where they get merged into the tools array alongside the built-in CLI and MCP tools and the dispatcher callback is called when the model invokes them.
Would it be possible to surface these two fields on the public SessionConfig? It would just be passing them through to the internal session, so no new logic is required since the all the plumbing is already there.
interface SessionConfig {
// ... existing fields ...
externalToolDefinitions?: ExternalToolDefinition[];
externalToolDispatcher?: ExternalToolDispatcher;
}