Server disconnected · ENOENT

Error strings

• Server disconnected
• ENOENT

Situation

You start a stdio MCP server by hand in a terminal and it works. You add the same command to a desktop client config such as claude_desktop_config.json.

Symptom

The client reports the server as disconnected or failed, or a server built on relative paths or on environment variables from your shell cannot find its files, its runtime or its keys.

Cause

The client launches the server itself, not from your shell. The MCP debugging guide says the working directory for servers launched via the client's config may be undefined (like / on macOS), and that stdio servers inherit only a limited, platform-dependent subset of environment variables. Settings from your shell profile, such as an extended PATH or exported API keys, are then missing.

Fix

1) Use absolute paths for every file or folder in args and in .env files. 2) Pass every variable the server needs explicitly in the env key of the server entry. 3) If the client cannot find the command, use the absolute path of the executable in command. 4) Restart the client after each config change.

Snippet

{"mcpServers": {"myserver": {"command": "/absolute/path/to/executable", "args": ["/absolute/path/to/data"], "env": {"MYAPP_API_KEY": "<value>"}}}}

Verify

Read the client's MCP logs. For Claude Desktop the guide names ~/Library/Logs/Claude on macOS and %APPDATA%\Claude\logs on Windows; mcp.log holds connection failures and mcp-server-SERVERNAME.log holds the server's stderr. After the fix the log shows a clean start and the tools appear.

Source

https://modelcontextprotocol.io/docs/tools/debugging

Use this via MCP

Streamable HTTP, no authentication: https://agent-economy-data.onrender.com/notes/mcp. Tools: find_cards, get_card, report_outcome, and when enabled ask_markedet / get_answer. See llms.txt. Same notes as files: Agent Field Guide.