[BUG] MCP Tool Search not activating - MCPSearch tool not available despite >10% context usage

Preflight Checklist

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

What's Wrong?

Version: 2.1.12 (native install, macOS)
Model: Opus 4.5

Problem:
MCP Tool Search is not activating despite MCP tools consuming ~31.6K tokens (15.8% of context window), which exceeds the 10% threshold.

When I ask Claude what tools are available, MCPSearch is not present. All MCP tools are being loaded upfront.

MCP Configuration:

• prod-ghl-mcp: HTTP transport, 36 tools (~19,650 tokens)
• n8n-mcp: HTTP transport, 20 tools (~6,575 tokens)
• plugin_supabase_supabase: 29 tools (~4,414 tokens)
• plugin_context7_context7: 2 tools (~917 tokens)

What I tried:

• Fresh install (uninstall + reinstall)
• Added "env": {"ENABLE_TOOL_SEARCH": "auto"} to settings.json
• Ran ENABLE_TOOL_SEARCH=auto claude and ENABLE_TOOL_SEARCH=true claude
• None of these caused MCPSearch to appear or reduced token usage

/doctor output shows:
⚠ Large MCP tools context (~31,556 tokens > 25,000)

What Should Happen?

MCPSearch tool should be available and MCP tools should be deferred/loaded on-demand.

Error Messages/Logs

Steps to Reproduce

1. Install Claude Code 2.1.12 (native install on macOS)
2. Add HTTP-based MCP servers to ~/.claude.json:

{
"mcpServers": {
"prod-ghl-mcp": {
"type": "http",
"url": "https://services.leadconnectorhq.com/mcp/",
"headers": {
"Authorization": "Bearer <token>",
"locationId": "<id>"
}
},
"n8n-mcp": {
"type": "http",
"url": "https://api.n8n-mcp.com/mcp"
}
}
}

1. Also have Supabase and Context7 plugins enabled (from marketplace)
2. Launch Claude Code with: ENABLE_TOOL_SEARCH=auto claude
3. Run /doctor - observe MCP tools consuming ~31,556 tokens (>10% of context)
4. Run /context - observe MCP tools: 31.6k tokens (15.8%)
5. Ask Claude: "What tools do you have available? Do you have MCPSearch?"
6. Observe that MCPSearch tool is NOT available - all MCP tools loaded upfront

Expected: MCPSearch tool should be present and MCP tools should be deferred (lazy loaded) since they exceed the 10% threshold.

Actual: No MCPSearch tool exists. All 87 MCP tools are loaded into context at startup, consuming 31.6k tokens.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.12

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_