Claude Code Skill Tool Internal Error

What this error means

[Tool result missing due to internal error] is a Claude Code failure pattern reported for developers trying to fix claude code skill tool returning internal error instead of executing. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Bug filed on anthropics/claude-code (issue #58413, created 2026-05-12). The Skill tool occasionally returns ‘[Tool result missing due to internal error]’ in long-running sessions. Retrying with nearly identical arguments succeeds. Labeled as bug + platform:windows. Reporter filed to leave a trace for others hitting the same issue.

Common causes

• In long-running Claude Code sessions, the Skill tool intermittently returns ‘[Tool result missing due to internal error]’ instead of executing the requested skill. This disrupts automated workflows and is unpredictable, making it hard to diagnose. Developers search for workarounds and root cause.
• Bug filed on anthropics/claude-code (issue #58413, created 2026-05-12). The Skill tool occasionally returns ‘[Tool result missing due to internal error]’ in long-running sessions. Retrying with nearly identical arguments succeeds. Labeled as bug + platform:windows. Reporter filed to leave a trace for others hitting the same issue.

Quick fixes

1. Confirm the exact error signature matches [Tool result missing due to internal error].
2. Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/anthropics/claude-code/issues/58413

Evidence note: Bug filed on anthropics/claude-code (issue #58413, created 2026-05-12). The Skill tool occasionally returns ‘[Tool result missing due to internal error]’ in long-running sessions. Retrying with nearly identical arguments succeeds. Labeled as bug + platform:windows. Reporter filed to leave a trace for others hitting the same issue.

Related errors

• Claude Code tool execution failed
• Claude Code skill not found error
• Claude Code internal server error

FAQ

What should I check first?

Start with the exact [Tool result missing due to internal error] text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Claude Code workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without [Tool result missing due to internal error].