sequential-thinking MCP flooding logs with thought output (DISABLE_THOUGHT_LOGGING)

TL;DR

The server logs thoughts to stderr by default, which lands in your CLI logs. Set DISABLE_THOUGHT_LOGGING=true in the server's env block. The model still receives thoughts through the tool protocol; only the stderr trace goes quiet.

The error

(stderr full of sequential thought traces on every tool call)

Fix it

1. Add the env var to your MCP config:

   {
     "mcpServers": {
       "sequential-thinking": {
         "command": "npx",
         "args": ["-y", "@modelcontextprotocol/server-sequential-thinking"],
         "env": { "DISABLE_THOUGHT_LOGGING": "true" }
       }
     }
   }

   • Expected: valid JSON.

2. Restart the client.

   • Expected: logs are clean; thinking still works in-chat.

When to use

• You run a CLI client and stderr thought traces pollute logs or CI output.
• You want the reasoning in-context but not in logs.

When NOT to use

• The model is not thinking at all - that is a client/tool-availability issue.
• You rely on the stderr trace for debugging - keep it on while debugging.

Compatibility

• @modelcontextprotocol/server-sequential-thinking.

Root cause

The server is passive: the model does the reasoning and the server just records it. The stderr trace is a debugging convenience that defaults on; the actual thought content flows through the tool result, which is unaffected by the flag.

Edge cases

• The value must be the string "true" in JSON env.
• If you later need to debug thought flow, remove the flag temporarily.