cc-error

Which Claude Code tools fail most often? Tracks is_error across all tool results to find failure patterns.

npx cc-error

Zero dependencies. Reads ~/.claude/projects/ directly.

Output

cc-error — Tool Failure Rates in Claude Code
====================================================
Sessions: 1,977 | 54.5% hit ≥1 error
Total calls: 143,714 | Errors: 6,444 (4.5% overall)

Error rate by tool (top 10, ≥10 calls):
  WebFetch                 ████████░░░░░░░░░░░░   24.8%  (378/1,523)
  KillShell                ██░░░░░░░░░░░░░░░░░░    8.0%  (2/25)
  Bash                     ██░░░░░░░░░░░░░░░░░░    6.1%  (3330/54,519)
  TaskOutput               ██░░░░░░░░░░░░░░░░░░    5.3%  (44/825)
  Read                     █░░░░░░░░░░░░░░░░░░░    4.2%  (1544/36,664)
  Glob                     █░░░░░░░░░░░░░░░░░░░    3.9%  (109/2,785)
  Edit                     █░░░░░░░░░░░░░░░░░░░    3.5%  (605/17,310)

What it tells you

• 54% of sessions hit at least one error — errors are the norm, not the exception
• WebFetch fails 25% of the time — blocked URLs, auth walls, timeouts. 1 in 4 web fetches fails
• Bash has 6% error rate — across 54K calls, that's 3,300 failed commands
• Read fails 4% — usually reading a file that doesn't exist yet
• Edit fails 3.5% — old_string not found in file
• 4.5% overall error rate means Claude handles ~1 error per 22 tool calls

Flags

npx cc-error          # tool failure rankings
npx cc-error --json   # raw JSON output

Browser version

yurukusa.github.io/cc-error — drag and drop your projects folder.

Part of cc-toolkit — tools for understanding your Claude Code sessions.

Source: yurukusa/cc-error