Why does the MCP hammer icon appear but show no tools?

The hammer (tools) icon appears when at least one server started successfully. If it shows zero tools, the server started but returned an empty tools list, or the tools/list call failed. Check the MCP log for that server. Common causes: a runtime error after startup, missing permissions for the server to access what it needs, or the server package itself has a bug. Try running the server command manually in a terminal to see its output.

Troubleshooting Claude Desktop Updated June 2026

MCP Tools Not Showing Up in Claude

Q: Why are MCP tools not showing up in Claude Desktop?

MCP tools do not appear when the server fails to start or fails to complete its initialization handshake with Claude Desktop. The most common causes: (1) the command binary was not found because Claude Desktop uses a restricted PATH - use absolute paths; (2) the config JSON has a syntax error that prevents all servers from loading; (3) the server crashed immediately due to a missing or invalid API key in the env block; (4) Claude Desktop was not fully quit before restarting after the config change.

Q: MCP tools showed up before but disappeared after an update - why?

An update to Claude Desktop or the MCP server package can break things. Check: (1) the log file for the server to see the new error; (2) whether the package was updated and broke compatibility; (3) whether Claude Desktop changed its config file location or format. Pin to a known-good version by specifying a version in args: ['-y', '@modelcontextprotocol/server-filesystem@1.0.0'] and test before upgrading.

Q: How do I see which MCP tools are available in Claude?

Click the hammer (tools) icon in the Claude Desktop chat input area. It shows a list of all available tools from all connected MCP servers. If the icon is not there, no servers connected successfully. If the icon is there but fewer tools appear than expected, some servers failed - check each server's log file.

Quick fix: MCP tools vanish when a server fails to start. Open the MCP log (~/Library/Logs/Claude/mcp-server-NAME.log on macOS), find the error, and fix it. The two most likely causes: a bare npx or uvx in your config that needs an absolute path, or a JSON syntax error in claude_desktop_config.json that disables every server silently.

How tools appear in Claude

When Claude Desktop starts, it reads claude_desktop_config.json, spawns each configured MCP server as a child process, and completes the MCP initialization handshake (which includes a tools/list call). Only servers that complete that handshake contribute tools to the UI. The hammer icon appears only if at least one server connected successfully.

This means: no hammer icon = all servers failed to start. Hammer icon with missing tools = some servers failed, or a server returned an unexpected tools list.

No hammer icon at all

Work through this checklist in order:

1. Validate your JSON config

# macOS/Linux
cat ~/Library/Application\ Support/Claude/claude_desktop_config.json | python3 -m json.tool

# Windows
Get-Content "$env:APPDATA\Claude\claude_desktop_config.json" | ConvertFrom-Json

A syntax error here silently disables all servers with no UI feedback. Fix any error before continuing.

2. Check you are editing the right file

The config must be at the exact path for your OS:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json
Linux: ~/.config/Claude/claude_desktop_config.json

3. Use absolute paths for commands

Claude Desktop does not inherit your terminal PATH. Replace:

// WRONG - will fail silently on most systems
"command": "npx"

// RIGHT - use the output of: which npx
"command": "/usr/local/bin/npx"

// RIGHT - Apple Silicon Mac (Homebrew)
"command": "/opt/homebrew/bin/npx"

// RIGHT - Windows
"command": "C:/Users/you/AppData/Roaming/npm/npx.cmd"

4. Fully quit and restart Claude Desktop

macOS: Cmd+Q (not Cmd+W). Windows: right-click the system tray icon → Quit. Closing the window does not stop the background process.

Hammer icon appears but shows no tools

This means at least one server started but returned an empty tools list or failed after initialization. Read the log:

tail -50 ~/Library/Logs/Claude/mcp-server-YOURSERVERNAME.log

Common causes:

Server crashed after starting — look for a Python traceback, Error: line, or 401/403 response in the log
Missing required file — filesystem server with a path that does not exist, sqlite server before the database file is created
npx first-run download — wait 60 seconds on first use; npx downloads the package before starting. Test by running the command manually in a terminal first
Wrong API key format — some servers validate the key format on startup and crash silently if it does not match the expected pattern

Fewer tools than expected

If you have three servers configured but only one set of tools appears, the other servers failed. Check each server's log file:

# List all MCP log files
ls ~/Library/Logs/Claude/mcp*.log

Each file is named mcp-server-SERVERNAME.log where SERVERNAME matches the key in your mcpServers config object. Open each file and find the most recent error.

Tip: Run the failing server command manually in your terminal to see its output directly. For example: /usr/local/bin/npx -y @modelcontextprotocol/server-github — this often shows a clearer error than the log file.

Tools disappeared after an update

Both Claude Desktop updates and MCP package updates can break server compatibility. To diagnose:

Check the log file for the now-failing server — the error will show what changed
If a package was auto-updated by npx -y, pin a known-good version: "args": ["-y", "@modelcontextprotocol/server-filesystem@1.0.3"]
If Claude Desktop itself updated, check the Anthropic changelog for MCP protocol version changes

Automated diagnosis: paste your claude_desktop_config.json into the free MCP Config Auditor to get a per-server report flagging bare commands, placeholder tokens, and JSON errors. 100% client-side.

To check live server health (does the server respond to MCP protocol calls?): MCP Server Health Check.

FAQ

Why are MCP tools not showing up in Claude Desktop?

Tools do not appear when servers fail to start. The most common causes: bare npx/uvx command that needs an absolute path, JSON syntax error in the config, missing or placeholder API key, or Claude Desktop not fully restarted. Read the MCP log file at ~/Library/Logs/Claude/mcp-server-NAME.log for the exact error.

Why does the hammer icon appear but show no tools?

The hammer icon shows when at least one server started. Zero tools means the server started but returned an empty list or crashed after initialization. Check the server log for runtime errors — missing files, invalid credentials, or a connection failure are the most common causes.

MCP tools showed up before but disappeared after an update — why?

Package updates via npx -y can silently break things. Pin a version in args: ["-y", "@modelcontextprotocol/server-NAME@1.0.0"] and check the server log for the specific error after the update.

How do I see which MCP tools are available in Claude?

Click the hammer icon in the chat input area. If the icon is absent, no servers connected. If fewer tools appear than expected, some servers failed — check each server log file.