[aluzzardi]

Mendral co-founder here and author of the post.

This is an interesting approach. I definitely agree with the problem statement: if the LLM has to filter by error/fatal because of context window constraints, it will miss crucial information.

We took a different approach: we have a main agent (opus 4.6) dispatching "log research" jobs to sub agents (haiku 4.5 which is fast/cheap). The sub agent reads a whole bunch of logs and returns only the relevant parts to the parent agent.

This is exactly how coding agents (e.g. Claude Code) do it as well. Except instead of having sub agents use grep/read/tail, they use plain SQL.

[buryat]

yeah, I saw Claude Code doing lots of grepping/find and was curious if that approach might miss something in the log lines or if loading small portion of interesting log lines into the context could help. I find frequently that just looking at ERROR/WARN lines is not enough since some might not actually be errors and some other skipped log lines might have something to look into.

And I just wanted to try MCP tooling tbh hehe Took me 2 days to create this to be honest

[aluzzardi]

From our experience running this, we're seeing patterns like these:

- Opus agent wakes up when we detect an incident (e.g. CI broke on main)

- It looks at the big picture (e.g. which job broke) and makes a plan to investigate

- It dispatches narrowly focused tasks to Haiku sub agents (e.g. "extract the failing log patterns from commit XXX on job YYY ...")

- Sub agents use the equivalent of "tail", "grep", etc (using SQL) on a very narrow sub-set of logs (as directed by Opus) and return only relevant data (so they can interpret INFO logs as actually being the problem)

- Parent Opus agent correlates between sub agents. Can decide to spawn more sub agents to continue the investigation

It's no different than what I would do as a human, really. If there are terabytes of logs, I'm not going to read all of them: I'll make a plan, open a bunch of tabs and surface interesting bits.

[synergy20]

did you create the subagent yourself?claude's agent never called haiku in my case