Claude Code / AI Coding Tools

Claude Code Skill Tool Internal Error

Fix Claude Code Skill tool returning internal error instead of executing Includes evidence for Claude Code troubleshooting demand.

Source-backed Last updated May 12, 2026 1 source Needs local verification

Category: AI Coding Tools
Error signature: [Tool result missing due to internal error]
Quick fix: Compare the failing environment with a known working setup, then change one configuration value at a time.
Updated: May 12, 2026
Verification status: Source-backed
Evidence: 1 public source URL

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for Claude Code, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

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

Confirm the exact error signature matches [Tool result missing due to internal error].
Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
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

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

Diagnostic flow for this page

Match [Tool result missing due to internal error] exactly before applying the quick fix.
Compare the failing environment with Claude Code versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does [Tool result missing due to internal error] mean in Claude Code?

[Tool result missing due to internal error] indicates the workflow described by "Claude Code Skill Tool Internal Error" failed in a AI Coding Tools context. Start by confirming the exact signature and the component that emitted it.

What should I check first for [Tool result missing due to internal error]?

Check whether this cause matches your environment: 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.

Is the [Tool result missing due to internal error] guidance source-backed?

The "Claude Code Skill Tool Internal Error" page is labeled source-backed. It has 1 public source URL from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for [Tool result missing due to internal error]?

For "Claude Code Skill Tool Internal Error", avoid applying "Compare the failing environment with a known working setup, then change one configuration value at a time." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging [Tool result missing due to internal error]?

For "Claude Code Skill Tool Internal Error", collect the failing Claude Code command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.