I’m currently working on a project where I’m assessing a multi-agent architecture as opposed to an existing single agent design. The multi-agent application utilizes LangGraph, and I’ve also added logging for both setups to monitor their interactions in LangSmith.
I’m encountering a problem with the multi-agent configuration. When examining the traces through the LangSmith interface, all nodes seem to be displayed correctly. However, when I attempt to access these nodes via the Run object during evaluations, I run into issues.
I can easily reach the Planner and ExecutionTeam nodes, but I can’t go any further. It appears that these nodes lack child runs and don’t return any outputs when accessed through the API, despite clearly showing data and child nodes on the web interface.
Has anyone experienced this problem? I’m curious if it’s a known limitation of LangSmith’s API or if there’s an error on my part that’s causing the difficulty with accessing the nested nodes.
I’ve encountered the same timing issue with LangSmith’s API in the past. The web interface displays all data correctly because it has more time to establish the trace hierarchy. When you access it through the Run object, you might be hitting the API prematurely before all the child relationships are indexed.
Consider introducing a slight delay before trying to access nested nodes, or implement a retry mechanism that checks for child runs every few seconds. LangGraph traces often take longer to appear in the API compared to single-agent flows, and I’ve observed they typically require additional seconds to fully materialize.
Also, ensure you are using the latest SDK version, as recent updates have addressed trace completeness issues, particularly in multi-agent environments.
Sounds like a pagination or depth issue with the LangSmith API. When you’re dealing with complex multi-agent traces, the API won’t return the full nested structure in one call - especially for deeply nested child runs. I ran into the same thing with LangGraph workflows. You’ve got to fetch child runs individually using their run IDs. The parent Run object has references to child run IDs, but you need separate API calls to get each child’s details and outputs. Check if your Run object has a child_run_ids property. Then loop through those IDs and fetch each child run one by one. The web interface does this automatically behind the scenes - that’s why you see everything there but not through direct API calls. Also double-check your API permissions include nested run data access. Some org settings restrict deep trace access.
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