[MODEL] Claude Opus 5 writes extremely slow filesystem scans for simple file lookups

Preflight Checklist

• [x] I have searched existing issues for similar behavior reports
• [x] This report does NOT contain sensitive information (API keys, passwords, etc.)

Type of Behavior Issue

Other unexpected behavior

What You Asked Claude to Do

Regular coding+review work where Claude encounters a symbol and tries to find its source file

What Claude Actually Did

Claude writes extremely inefficient search commands scanning the entire filesystem instead of a simple search command scoped to the working directory / repository, example:

find / -name "TYPENAME.cs" -not -path "*/obj/*" 2>/dev/null | head -3; grep -rn "METHODNAME" --include=*.cs -r ~/.nuget 2>/dev/null | head -3

Expected Behavior

Claude should scope file search commands to the current repository, and only fall back to less efficient methods when a quick scan finds nothing

Files Affected

Permission Mode

Accept Edits was OFF (manual approval required)

Can You Reproduce This?

Yes, every time with the same prompt

Steps to Reproduce

Any type of coding work (in a C# repo), this happened in 3/4 of my sessions today using Claude Opus 5.

Claude Model

Opus

Relevant Conversation

Impact

Low - Minor inconvenience

Claude Code Version

2.1.220 (Claude Code)

Platform

Anthropic API

Additional Context

Claude seems to assume the symbol it's searching for lives in an external dependency based on non-semantic context (it assumes a type lives in a specific namespace based on the file's usings, and has no roslyn integration to verify this), and tries a wide scan before doing a quick repo-local scan to validate this assumption.