[BUG] `find` tool returns "Anthropic client not available" error With Claude Cowork

🐛 Bug Report: find tool returns "Anthropic client not available" error

Summary

The mcp__Claude_in_Chrome__find tool consistently fails with the error message "Anthropic client not available. Please check your API configuration." while all other MCP Chrome tools work correctly.

Environment

| Item | Value |
|------|-------|
| Platform | Claude Desktop App (Cowork mode) |
| OS | Linux claude 6.8.0-90-generic (aarch64) |
| Date | 2026-01-13 |
| MCP Server | Claude in Chrome |

Steps to Reproduce

1. Open Claude Desktop App in Cowork mode
2. Connect to Chrome browser via MCP (tabs_context_mcp works fine)
3. Navigate to any webpage (e.g., https://claude-world.com)
4. Use the find tool to search for any element

Minimal Reproduction Code

// Step 1: Get tab context (WORKS)
{
  "tool": "mcp__Claude_in_Chrome__tabs_context_mcp",
  "parameters": {}
}
// Returns: {"availableTabs":[{"tabId":222397199,"title":"...","url":"https://claude-world.com/"}]}

// Step 2: Take screenshot (WORKS)
{
  "tool": "mcp__Claude_in_Chrome__computer",
  "parameters": {
    "action": "screenshot",
    "tabId": 222397199
  }
}
// Returns: Successfully captured screenshot

// Step 3: Use find tool (FAILS)
{
  "tool": "mcp__Claude_in_Chrome__find",
  "parameters": {
    "tabId": 222397199,
    "query": "Subscribe button"
  }
}
// Returns: ERROR

Expected Behavior

The find tool should return a list of matching elements on the page, similar to:

{
  "elements": [
    {
      "ref": "ref_123",
      "type": "button",
      "text": "Subscribe",
      "location": {...}
    }
  ]
}

Actual Behavior

The tool returns an error:

Failed to find element: Anthropic client not available. Please check your API configuration.

Error Details

| Attempt | Query | Result |
|---------|-------|--------|
| 1 | "Subscribe button" | ❌ Anthropic client not available |
| 2 | "Discord" | ❌ Anthropic client not available |
| 3 | "email input" | ❌ Anthropic client not available |

Working vs Non-Working Tools

✅ Working MCP Tools

| Tool | Status | Notes |
|------|--------|-------|
| tabs_context_mcp | ✅ Works | Returns tab information correctly |
| tabs_create_mcp | ✅ Works | Creates new tabs |
| navigate | ✅ Works | Navigation works (with user permission) |
| computer (screenshot) | ✅ Works | Screenshots captured successfully |
| computer (scroll) | ✅ Works | Scrolling works with coordinates |
| read_page | ✅ Works | Returns DOM structure correctly |
| get_page_text | ✅ Works | Extracts page text content |
| form_input | ✅ Works | Form filling works |

❌ Non-Working MCP Tools

| Tool | Status | Error |
|------|--------|-------|
| find | ❌ Fails | "Anthropic client not available" |

Analysis

The error message suggests that the find tool requires an Anthropic API client internally (possibly for natural language element matching using AI), but this client is not properly initialized or configured in the current environment.

Possible Root Causes

1. Missing API Key: The Anthropic API key may not be passed to the MCP server for the find tool
2. Configuration Issue: The MCP server configuration may not include the necessary API credentials for AI-powered element finding
3. Internal Dependency: The find tool may have an internal dependency on an Anthropic client that other tools don't require
4. Environment Variable: Required environment variable (e.g., ANTHROPIC_API_KEY) may not be accessible to the MCP server

Suggested Fix

1. Ensure the Anthropic API credentials are properly passed to the MCP Chrome server
2. Check if the find tool requires additional configuration compared to other tools
3. Consider adding a fallback mechanism when AI-powered finding is unavailable

Workaround

Currently, users can use read_page to get the DOM structure and manually search for elements by their ref_id:

{
  "tool": "mcp__Claude_in_Chrome__read_page",
  "parameters": {
    "tabId": 222397199,
    "filter": "interactive"
  }
}

Then use the returned ref_id values with other tools like computer or form_input.

Impact

• Severity: 🔴 High
• Affected Users: All users of Claude in Chrome MCP server
• Functionality Impact: Cannot use natural language to find page elements, must manually parse DOM structure

Screenshots

Page Being Tested


Error Reproduction

Query: "Subscribe button"
Error: Failed to find element: Anthropic client not available. Please check your API configuration.

Query: "Discord"
Error: Failed to find element: Anthropic client not available. Please check your API configuration.

Query: "email input"
Error: Failed to find element: Anthropic client not available. Please check your API configuration.

Additional Context

• All other MCP Chrome tools work correctly in the same session
• The error is 100% reproducible
• The error occurs regardless of the query content
• The tab connection is valid (other tools work with the same tabId)

---

Reporter: Claude AI (Automated Testing)
Date: 2026-01-13
Test Session: Cowork Bug Testing - 10,000 Test Cases Project

Confirming this affects ALL MCP servers in Cowork, not just Chrome MCP

I'm experiencing the same issue but across every MCP type:

OAuth Connector MCPs (remote):

Examples: Figma, CoinGecko return 403 Forbidden
Notably, CoinGecko's get_global endpoint requires no authentication, yet still 403s - indicating the block is happening at Anthropic's proxy layer, not the MCP server

stdio/mcp-remote MCPs (local config via claude_desktop_config.json):

SSH MCP server via mcp-remote
Tools don't register at all: Error: No such tool available

Remote MCPs work perfectly in:

Claude Desktop (chat mode)
Claude Code CLI
Claude Web
Claude Mobile

Local MCPs work perfectly in:

Claude Code CLI
Claude Desktop (chat mode)

This suggests Cowork's VM uses a separate MCP routing infrastructure that is:

Not forwarding OAuth tokens to connector MCPs (explains 403s)
Not establishing stdio/mcp-remote connections or registering their tools

The 403 on an unauthenticated endpoint looks like a smoking gun - requests aren't reaching the MCP servers at all.

@dial481 This should be fixed in latest Claude Desktop. Please update to latest (v1.1.799) and ping me below if the issue remains. Closing this out for now

Hi @MarshallOfSound thanks. Remote "connector" MCPs work. But MCPs that run locally (or via mcp-remote which runs locally) are not seen by Claude Cowork but work in Chat still.

My Claude desktop version: Claude 1.1.762 (35ba62) 2026-01-23T05:17:27.000Z

The agent just says it doesn't see these tools at all. Also sometimes the on/off switches are broken and cannot be changed in Cowork mode, only in Chat.

Oops, sorry @MarshallOfSound I just noticed I am not on the version you mentioned above, but my app says I am on the latest...

<img width="251" height="162" alt="Image" src="https://github.com/user-attachments/assets/0b4a0c0b-9791-4673-8f32-5303915880b2" />

@MarshallOfSound today I have Claude 1.1.799 (2e02b6) 2026-01-23T19:08:29.000Z

But the problem with local mcp servers persists. The agent just doesn't see them. And the on/off toggles are broken in Cowork mode. Everything is working in Chat.

Still not working as of Claude 1.1.1093 (5a5517) 2026-01-27T17:57:04.000Z. New issue: #20377

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.