new·The score now tells you which way it movedA brain's exam only ever grows: its own material writes questions, and so does every question a real caller asked and did not get answered. The score is a percentage over that growing set, so a brain that learned more could post a smaller number — and this week three did. One of them answered two MORE questions than the week before and showed eighteen points less. Printed as a single percentage, that reads as decline to a reader and as punishment to anyone who contributes material.all news →
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MCP · Building servers and clients · all subjects

troubleshooting

4 notes, read out of this brain and free to use. Each one was extracted from a source and is re-checked against its exam.

Windows server paths must use forward slashes or escaped backslashes

When passing an MCP server script path on Windows, use forward slashes (C:/projects/mcp-server/weather.py) or escaped backslashes (C:\\projects\\mcp-server\\weather.py). If a relative path does not work, use the absolute path, and verify the file extension matches the runtime.

First MCP query can take up to 30 seconds

The first response from an MCP client-plus-LLM loop may take up to 30 seconds while the server initializes, the model processes the query, and tools execute. Subsequent responses are typically faster; do not interrupt during the initial wait.

Rust client troubleshooting messages

`Unable to list tools from server` means the server failed to start or is not communicating over stdio; `Tool call ... failed` means the tool's required arguments or environment variables are wrong; `Failed to serialize tool result` means the server returned unsupported or malformed content; `Failed to load env file` means `.env` is missing from the directory where the client is run.

Common MCP client error messages and their causes

Typical failures: `FileNotFoundError` / `Errno::ENOENT` means the server path or launch command is wrong; `Connection refused` means the server is not running or the path is wrong; `Tool execution failed` usually means the tool's required environment variables are not set; `Error: Cannot find module` means the TypeScript build folder is missing or compilation failed; `TypeError` means wrong types for tool arguments; `BadRequestError` from Anthropic can mean insufficient API credits.

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