MCP server exits with 'unknown command' or a usage error

If the start command in your MCP config is wrong for the installed version, the server prints a usage error and exits. Your client then only reports that the connection closed. We recorded this for 3 servers we list and for Prisma CLI MCP's 8.0.0-rc.33 prerelease. A further 3 packages had no runnable entry point at all.

Short answer

Run the exact command from your config in a terminal and read the usage line. If a new release dropped the command, pin the last version that has it: prisma@7.10.1 still started prisma mcp for us. If the server needs a subcommand, add it to args.

Last tested 2026-11-11

How we test: methodology. Context cost: lowest context cost MCP servers. Not tested by us: security, output quality, and behaviour with real credentials.

Symptom

The server exits right after the client starts it. Its stderr shows Unknown command, No command registered, arguments are required or a usage line.

The exact errors we saw

Server	What it printed (verbatim)	Where we saw it	Tested
Prisma CLI MCP `prisma 8.0.0-rc.33`	✘ [CLI.UNKNOWN_COMMAND] No command registered for `mcp`, did you mean `lsp`?	stderr of prisma mcp (exited code 2)	2026-11-11
Cloudflare `@cloudflare/mcp-server-cloudflare 0.2.0`	`Unknown command: undefined. Expected 'init' or 'run'.`	stderr/stdout at launch (process exited)	2026-11-10
codenib CodeGraph `codenib 0.2.5`	`error: the following arguments are required: command`	stderr/stdout at launch (process exited)	2026-11-10
Neon (official) `@neondatabase/mcp-server-neon 0.6.5`	`Invalid number of arguments`	stderr/stdout at launch (process exited)	2026-11-10
Filesystem (cyanheads) `@cyanheads/filesystem-mcp-server 1.0.4`	`no bin entry`	our test client: the installed package declares no executable	2026-11-10
Memory (Python) `mcp-server-memory 0.0.1`	`no bin entry`	our test client: the installed package declares no executable	2026-11-10
Sanity `@sanity/mcp-server 0.12.2`	`no bin entry`	our test client: the installed package declares no executable	2026-11-10

Cause

A release dropped or renamed the command. On 2026-11-11 npm's latest for prisma installed 8.0.0-rc.33, and that CLI has no mcp command. Pinned to 7.10.1, prisma mcp started and listed 3 tools (migrate-status, migrate-dev, Prisma-Studio). We list that pin as Prisma CLI MCP.
The server needs a subcommand or argument. Cloudflare's error names init and run. codenib's usage line lists its subcommands, one of them mcp. Neon printed Invalid number of arguments.
No bin entry. This is our test client's message, not the server's. The package installed but declares no executable, so npx or uvx had nothing to run.

Fix

See what latest points at. Run npm view <package> dist-tags (npm view, npm dist-tag). If latest lacks the command, pin a version that has it, for example npx -y prisma@7.10.1 mcp. This pin worked in our test.
Add the subcommand or argument that the usage line or README names to args in your MCP config. not tested by us
No runnable entry point: check the README for the real start command or package name. npx can run a named binary from a package with npx -y --package=<pkg> <bin> (npx). not tested by us

Affected listings

Prisma CLI MCP (prisma, tested 2026-11-11, status working)
Cloudflare (@cloudflare/mcp-server-cloudflare, tested 2026-11-10, status failed)
codenib CodeGraph (codenib, tested 2026-11-10, status failed)
Neon (official) (@neondatabase/mcp-server-neon, tested 2026-11-10, status failed)
Filesystem (cyanheads) (@cyanheads/filesystem-mcp-server, tested 2026-11-10, status failed)
Memory (Python) (mcp-server-memory, tested 2026-11-10, status failed)
Sanity (@sanity/mcp-server, tested 2026-11-10, status failed)

More troubleshooting: all troubleshooting pages · MCP error -32000: Connection closed · MCP servers that need an API key or sign-in. Quotes are verbatim from our own test logs (colour codes removed; a trailing … marks a shortened line). We have not run these servers inside Claude Code, Claude Desktop or Cursor.

FAQ

Why does my MCP server say unknown command?

The command in your config doesn't exist in the installed version. In our tests Prisma 8.0.0-rc.33, which npm installed as latest on 2026-11-11, had no mcp command, while 7.10.1 did.

How do I pin an older version in an MCP config?

Put the exact version in the package name in args, for example npx -y prisma@7.10.1 mcp. That is the pin that started for us.

What does 'no bin entry' mean?

It is our test client's message: the package installed but declares no executable, so npx or uvx had nothing to start.