TL;DR: “how many mistakes” barely moved. “How dumb were the mistakes” moved a lot, and that’s what makes a tool feel like it got worse. Setup: Claude Code, Opus 5.5, auto mode, ~69 sessions over 12 days across 9 personal projects. I asked Claude to go through its own transcripts and measure whether the last 2 days were worse than the 10 days before. Raw error count: roughly flat Claude read every one of my messages and counted the ones where I had to correct it.
- Sessions with at least one mistake: 80% before, 78% in the last 2 days
- Corrections per 100 of my messages: 12.6 before, 15.4 now (+22%)
- Per session: 2.0 vs 2.1 On these numbers alone you would say “nothing changed”. That was wrong. Severity: clearly up Counting every mistake the same hides the difference. So we counted the messages where I was clearly irritated.
- Previous 10 days: 10 such messages, 1.2% of all my messages
- Last 2 days: 10 such messages, 4.0%
- That’s 3.3x more often per message and 5x more often per day What changed is the kind of mistake. Before, what annoyed me most was guessing and unnecessary questions during design discussions. In the last 2 days it failed at simple things:
- a small HTML table fix that took ~10 rounds (over $1)
- calculations that silently assumed something I never asked for, or left out a rule that was already agreed
- a caching proposal that ignored the obvious fact that the data doesn’t change for days
- a bug introduced in a small test And it repeated mistakes I had already pointed out (leaving the most recent data out of an evaluation for the 3rd time, breaking a formatting rule it knows). It’s not about long sessions I assumed the errors mostly came late in long sessions. The data says no:
- Before: corrections after 15.7% of my messages under 50k tokens of context, 5.5% above 150k
- Last 2 days: 10.4% under 50k, 17.4% at 50-150k Errors in the first 1-3 prompts of a session were actually less common (13% of errors vs 23% before). Technical causes we checked
- Same model (Opus 5.5) and the same auto mode for the whole period.
- The CLI went from 2.1.312 to 2.1.316 exactly when the bad 2 days started. The changelog has nothing about default effort, thinking or model behaviour for normal sessions, so for now it’s only a coincidence in timing.
- Output tokens per turn (thinking included): median -15%, mean -26% in the last 2 days, but only -5% per API call. That could mean shallower turns or just different tasks. The thinking text itself isn’t stored in the transcripts, so effort can’t be measured directly. Caveats: Claude classified its own mistakes (possible bias), the irritation count is keyword-based, the samples are small, and only mistakes I noticed are counted. Anyone else seeing this over the last few days? submitted by /u/kosio-dev
Originally posted by u/kosio-dev on r/ClaudeCode
You must log in or # to comment.