cc-error — Tool Failure Rates in Claude Code

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54.5%

of Claude Code sessions hit at least one error
4.5% overall error rate across 143K+ tool calls

1,977

Sessions

143K

Tool calls

6,444

Total errors

4.5%

Overall error rate

Error rate by tool

Tools with ≥10 calls, ranked by error rate

WebFetch

24.8%

378/1,523

Bash

6.1%

3,330/54,519

TaskOutput

5.3%

44/825

Read

4.2%

1,544/36,664

Glob

3.9%

109/2,785

Edit

3.5%

605/17,310

WebSearch

3.5%

85/2,443

What this means

54% of sessions have ≥1 error — errors are the norm, not the exception in Claude Code
WebFetch fails 25% of the time — blocked URLs, auth walls, and timeouts hit constantly
Bash: 6.1% × 54K calls = 3,300 failures — commands that exit non-zero, pipes that break
Read: 4.2% — usually reading a file path that doesn't exist yet
Edit: 3.5% — old_string not found in file is the most common cause
Claude handles errors gracefully — 4.5% errors on 143K calls means 1 failure per ~22 tool calls