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[BUG] API Error 400: "tool_use ids must be unique" when using -p flag with tool-requiring prompts #20508

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[BUG] API Error 400: "tool_use ids must be unique" when using -p flag with tool-requiring prompts#20508
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area:apiarea:toolsbugSomething isn't workinghas reproHas detailed reproduction stepsplatform:macosIssue specifically occurs on macOS

Description

@siliconcat
siliconcat
opened on Jan 24, 2026

Preflight Checklist

  • I have searched existing issues and this hasn't been reported yet
  • This is a single bug report (please file separate reports for different bugs)
  • I am using the latest version of Claude Code

What's Wrong?

When using claude -p (print mode) with prompts that require tool use (like checking if a file exists or running shell commands), the CLI fails with an API error about duplicate tool_use IDs.

Environment

  • Claude Code version: 2.1.19
  • OS: macOS Darwin 25.2.0
  • Shell: zsh

What Should Happen?

Claude should check if the file exists and return the result.

Error Messages/Logs

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.1.content.1: `tool_use` ids must be unique"},"request_id":"req_011CXRMKYvALAsgksCjT7HoC"}

Steps to Reproduce

Steps to Reproduce

claude -p "check package.json exists"

Pattern Observed

  • FAILS: Prompts requiring tool use ("check package.json exists", "echo hello")
  • WORKS: Pure text responses ("2+2", "say hello", "how many r in strawberry")

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.18

Claude Code Version

2.1.19

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

IntelliJ IDEA terminal

Additional Information

No response

Activity

  1. siliconcat
    added
    bugSomething isn't working
    on Jan 24, 2026
  2. github-actions
    added
    has reproHas detailed reproduction steps
    platform:macosIssue specifically occurs on macOS
    area:tools
    area:api
    on Jan 24, 2026

  3. github-actions commented on Jan 24, 2026

    @github-actions
    github-actionsbot
    on Jan 24, 2026 – with GitHub Actions

    Found 3 possible duplicate issues:

    1. [BUG] --print mode generates duplicate tool_use IDs causing API error 400 #16340
    2. [BUG] API Error 400 "tool use concurrency issues" occurs only in print mode (-p), not in interactive mode #18131
    3. [BUG] Claude keeps crashing when I ask it to stop and or clarify what it is doing #13124

    This issue will be automatically closed as a duplicate in 3 days.

    • If your issue is a duplicate, please close it and 👍 the existing issue instead
    • To prevent auto-closure, add a comment or 👎 this comment

    🤖 Generated with Claude Code

  4. siliconcat commented on Jan 24, 2026

    @siliconcat
    siliconcat
    on Jan 24, 2026
    Author

    while it seems to be the same as #16340 that one has been marked as completed without a solution. Downgrading to 2.1.18 solves the problem, but 2.1.19 fails.

  5. kenfdev commented on Jan 24, 2026

    @kenfdev
    kenfdev
    on Jan 24, 2026

    I posted a similar issue #20573 but probably it was a duplicate of this issue.

    I'll add a little more context.

    After a fresh login (deleting ~/.claude.json), the first prompt to claude -p works correctly, but any subsequent prompt fails with an API error about duplicate tool_use IDs. Simple prompts like claude -p "hello" work.

    The following steps always reproduces the problem:

    1. Delete ~/.claude.json to reset state
    2. Run claude and complete login
    3. Run a prompt: claude -p "check what tasks you have" - works
    4. Run the same or any other prompt again: claude -p "check what tasks you have" - fails

  6. matchpoint-ai-bot commented on Jan 24, 2026

    @matchpoint-ai-bot
    matchpoint-ai-bot
    on Jan 24, 2026

    Environment

    • Claude Code: 2.1.19 (regression)
    • OS: Ubuntu 22.04.5 LTS (GNU/Linux 6.8.0-90-generic x86_64)
    • Node: v22.22.0

    Behavior

    • Print mode (-p) tool use fails with: API 400 "tool_use ids must be unique"

    Repro
    claude --dangerously-skip-permissions -p "Use Read tool to read ./README.md" --output-format stream-json --verbose

    Workaround

    • Downgraded to 2.1.17: print-mode tool use works again

    Extra

    • Non-interactive claude doctor hangs at "Checking installation status..." here.

  7. matchpoint-ai-bot commented on Jan 24, 2026

    @matchpoint-ai-bot
    matchpoint-ai-bot
    on Jan 24, 2026

    Follow-up (Ubuntu 22.04.5, node v22.22.0):

    • 2.1.19 fails on the first tool call in -p (no multi-turn required).
    • 2.1.17 works end-to-end: ./ralph.py --max 1 --marker RALPH_217_OK "Use exactly one tool call to run 'touch /tmp/ralph_217_tool_ok', then output RALPH_217_OK." created the file and returned the marker.
    • claude doctor hangs at "Checking installation status..." here.

  8. EdgarHApollo commented on Jan 26, 2026

    @EdgarHApollo
    EdgarHApollo
    on Jan 26, 2026

    Additional Debug Findings

    I can confirm this issue on v2.1.19. Rolling back to v2.1.17 resolves the problem.

    Environment

    • Claude Code: 2.1.19 (broken) → 2.1.17 (working)
    • OS: macOS Darwin 22.6.0 (arm64)
    • Auth: OAuth (Max subscription)

    Debug Log Analysis

    Examining ~/.claude/debug/ logs reveals anomalous behavior when tool use is triggered:

    ~350 log entries at the exact same millisecond timestamp:
    2026-01-26T16:57:17.756Z [DEBUG] [API:request] Creating client...
    2026-01-26T16:57:17.756Z [DEBUG] [API:request] Creating client...
    2026-01-26T16:57:17.756Z [DEBUG] [API:request] Creating client...
    ... repeated 100+ times

    Breakdown:

    • 106 [API:request] Creating client calls
    • 212 [API:auth] OAuth token check calls (start + complete)

    This suggests a race condition or runaway loop in the tool initialization code that's generating duplicate IDs.

    Reproduction

    # Fails - any tool use
echo "Read test.txt" | claude --print --no-session-persistence

# Works - no tool use
echo "Say hello" | claude --print --no-session-persistence

Flags that DON'T help

- --no-session-persistence
- --dangerously-skip-permissions
- Different models (--model claude-sonnet-4-...)
- Clean directories without .claude settings
- Fresh reinstall of CLI

Workaround

ln -sf ~/.local/share/claude/versions/2.1.17 ~/.local/bin/claude

This completely resolves the issue. v2.1.17 handles tool use correctly.

  9. miohtama commented on Jan 26, 2026

    @miohtama
    miohtama
    on Jan 26, 2026

    I can confirm the downgrade to v2.1.17 solved the issue for me.

    For Visual Studio Code, you can use Extensions: Install Specific Version of Extension... in the command palette to pin down Claude Code to a working version.

  10. matthew-bram
    marked [BUG] Claude CLI 2.1.19 - Duplicate tool_use IDs with multiple --allowedTools #20885 as a duplicate of this issue on Jan 28, 2026

  11. matthew-bram commented on Feb 5, 2026

    @matthew-bram
    matthew-bram
    on Feb 5, 2026

    Has anyone seen any movement on this?

  12. github-actions
    added
    staleIssue is inactive
    on Feb 20, 2026

  13. starkey-01 commented on Feb 24, 2026

    @starkey-01
    starkey-01
    on Feb 24, 2026

    I'm experiencing this same issue on Claude Code on Android and web.

    API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.7.content.3: tool_use ids must be unique"},"request_id":"<id>"}
  14. github-actions
    removed
    staleIssue is inactive
    on Feb 24, 2026

  15. BenjaminCes commented on Mar 2, 2026

    @BenjaminCes
    BenjaminCes
    on Mar 2, 2026

    same error here!

  16. zernie commented on Mar 6, 2026

    @zernie
    zernie
    on Mar 6, 2026

    The worst thing is that you can't avoid this one in Claude code web

  17. malachany commented on Mar 7, 2026

    @malachany
    malachany
    on Mar 7, 2026

    I have this error in Claude Code Cloud while on mobile

  18. WynnD commented on Mar 12, 2026

    @WynnD
    WynnD
    on Mar 12, 2026

    I am also consistently hitting this wall

  19. acehox commented on Mar 12, 2026

    @acehox
    acehox
    on Mar 12, 2026

    Same issue here, also on mobile

  20. zernie commented on Mar 13, 2026

    @zernie
    zernie
    on Mar 13, 2026

    I'm getting this more and more often. No idea what's causing it. Even compaction doesn't help

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