'Not connected' error for Sequential Thinking MCP server in Cline on Windows
On Windows 11, I added the Sequential Thinking MCP server to Cline. Running npx -y @modelcontextprotocol/server-sequential-thinking prints 'Sequential Thinking MCP Server running on stdio', but Cline shows 'Error executing MCP tool: Not connected'. Why does this happen and what can I do about it?
Originally asked on GitHub: https://github.com/modelcontextprotocol/servers/issues/644
6 answers
Status: explained. The maintainers closed this issue as superseded by the v2 release of the reference servers. They noted that this was a pre-v2 report, that no defect was identified in the current server, and that the described behavior has either been fixed or no longer exists in the same form. If the problem still happens with the v2 release, the maintainers ask for a fresh issue with the version and reproduction steps.
The thread does not establish a single root cause. One commenter pointed out that Cline's auto-added config used the package name '@modelcontextprotocol/server-sequentialthinking' (missing the last hyphen), and suggested changing it to '@modelcontextprotocol/server-sequential-thinking'. That correction was not confirmed as fixing the error, but it is worth checking because a wrong package name would make npx launch an unexpected server.
Two workarounds were reported as working:
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Pin an older version of the server package. One commenter used '@modelcontextprotocol/server-filesystem@0.6.2' as an example and said that worked for that server.
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Clone the servers repository, go into the 'src/sequentialthinking' folder, run 'npm install' and 'npm run build', then point the MCP config at the built file with the node command. On Windows, the config used: command 'node' with args ['C:\Users\mypc\Documents\dev\mcp_servers\servers\src\sequentialthinking\dist\index.js']. A macOS user used the same approach with an absolute path to the node binary and the dist/index.js file.
General advice: when using npx-based MCP servers, verify the exact npm package name and check the client's full MCP logs, because a server can print 'running on stdio' and still crash immediately after connecting.
Did this work for you?-
What a GitHub user tried on GitHub (Didn't work)
The reporter ran 'npx -y @modelcontextprotocol/server-sequential-thinking' manually; it printed that the server was running, but Cline still reported 'Error executing MCP tool: Not connected'.
Source: https://github.com/modelcontextprotocol/servers/issues/644 (opens external site)
Did this work for you?What @zhaoyim tried on GitHub (Outcome unclear)
A commenter noticed Cline's auto-added config used the wrong package name '@modelcontextprotocol/server-sequentialthinking' and suggested changing it to '@modelcontextprotocol/server-sequential-thinking'.
Did this work for you?What @bobtista tried on GitHub (Worked)
A commenter said pinning an older version, for example '@modelcontextprotocol/server-filesystem@0.6.2', worked as a workaround for the same class of failure.
Did this work for you?What @sevonade4 tried on GitHub (Worked)
A commenter cloned the servers repo, ran 'npm install' and 'npm run build' inside the sequentialthinking folder, and configured the MCP server to run 'node .../sequentialthinking/dist/index.js' on Windows.
Did this work for you?What @shengr1225 tried on GitHub (Worked)
A commenter on macOS used the same clone-and-build approach, pointing the config at the absolute node binary path and the built 'dist/index.js' file.
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