Filetype

Tool Name: files/filetype

Returns a file's MIME type, like file -b --mime-type, detected natively from its first 8 KiB (no file(1) needed); read-only, path must be absolute. A symlink is reported as inode/symlink (never followed); directories, devices, fifos and sockets as inode/.... Use it before files/read, which refuses binary files. For size, permissions or ownership use files/list; for contents files/read. The reply is always one plain-text line (no output_format). privileged: true (a grant, and for root a paths: entry) reads files your account cannot.

Directories, devices, FIFOs, sockets and empty files get file's inode/* types; a symlink is reported as inode/symlink, not followed (as file does).
ELF binaries: application/x-executable, application/x-pie-executable, application/x-sharedlib, application/x-object, application/x-coredump.
Archives and compressors (gzip, bzip2, xz, zstd, 7z, lz4, tar, ar), .deb, .rpm, SQLite, PDF, images, audio/video and fonts the Go standard library knows, WebAssembly; #! scripts by interpreter (text/x-shellscript, text/x-script.python, text/x-perl, ...); JSON; otherwise text/plain or application/octet-stream.

file's libmagic knows far more formats (C source, makefiles, office documents, ...); for those this answers the generic text/plain or application/octet-stream. On 209 system binaries, libraries, configs and compressed docs of Ubuntu 24.04 (amd64 and arm64) the answers are identical to file's.

Arguments

Argument	Type	Required	Description
`path`	string	yes	Absolute path to the file
`privileged`	boolean	no	Run as root. Needs a grant for this tool in mcp-sudo.yaml and a `paths:` entry covering the path, otherwise refused

Example

Every example below shows the equivalent linuxctl command and the raw MCP JSON-RPC call it resolves to. The raw call always follows the same two-step pattern (see MCP API overview for the full explanation): open an SSE stream to get a one-time POST endpoint, then POST the JSON-RPC request there - the result streams back on the SSE connection.

Output captured live on an Ubuntu 24.04 host - every answer below matches file -b --mime-type there.

linuxctl

linuxctl get files filetype /usr/bin/ls

Output:

application/x-pie-executable

More answers from the same host:

/etc/hosts                                text/plain
/usr/bin/ls                               application/x-pie-executable
/usr/lib/x86_64-linux-gnu/libc.so.6       application/x-sharedlib
/usr/bin/lsb_release                      text/x-shellscript
/usr/share/doc/bash/changelog.Debian.gz   application/gzip
/etc/ssl/certs                            inode/directory
/usr/bin/python3                          inode/symlink

curl (raw MCP JSON-RPC)

# 1. Open the SSE stream (in the background) and capture the one-time POST endpoint
curl -N -s --cacert mcpd.crt -H "Authorization: Bearer $MCP_TOKEN" https://localhost:9091/sse &
# server sends: event: endpoint / data: /message?session_id=...

# 2. POST the tools/call request to that endpoint
curl -s --cacert mcpd.crt -X POST "https://localhost:9091/message?session_id=<from step 1>" \
  -H "Authorization: Bearer $MCP_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc": "2.0", "id": "1", "method": "tools/call", "params": {"name": "files/filetype", "arguments": {"path": "/usr/bin/ls"}}}'

# 3. The result arrives on the SSE stream opened in step 1

Response:

{
  "jsonrpc": "2.0",
  "id": "1",
  "result": {
    "content": [
      {
        "type": "text",
        "text": "application/x-pie-executable\n"
      }
    ]
  }
}

Arguments​

Example​

Arguments

Example