Is there a tool to view a torrent file?

You can use transmission-show, included in the Gnome Transmission BitTorrent client.

$ transmission-show amd64cd-5.1.2.iso.torrent
Name: amd64cd-5.1.2.iso
File: amd64cd-5.1.2.iso.torrent

GENERAL

  Name: amd64cd-5.1.2.iso
  Hash: e30c05f2330ba4869eefb90bf5978a505303b235
  Created by: 
  Created on: Sun Feb  5 01:31:29 2012
  Piece Count: 967
  Piece Size: 256.0 KiB
  Total Size: 253.3 MB
  Privacy: Public torrent

TRACKERS

  Tier #1
  http://tracker.netbsd.org:6969/announce

FILES

  amd64cd-5.1.2.iso (253.3 MB)

If you're using an older version of Transmission, you can use the older transmissioncli --info command:

$ transmissioncli --info amd64cd-5.1.2.iso.torrent
Transmission 2.03 (11030) - http://www.transmissionbt.com/
hash:   e30c05f2330ba4869eefb90bf5978a505303b235
name:   amd64cd-5.1.2.iso

tracker tier #1:
        announce:       http://tracker.netbsd.org:6969/announce
size:   253325312 (966 * 262144 + 94208)
file(s):
        amd64cd-5.1.2.iso (253325312)

btshowmetainfo, formerly included in the BitTorrent distribution but now largely installed with BitTornado (a fork of the BitTorrent 3.x codebase), does just that.

$ btshowmetainfo amd64cd-5.1.2.iso.torrent 
btshowmetainfo 20030621 - decode BitTorrent metainfo files

metainfo file.: amd64cd-5.1.2.iso.torrent
info hash.....: e30c05f2330ba4869eefb90bf5978a505303b235
file name.....: amd64cd-5.1.2.iso
file size.....: 253325312 (966 * 262144 + 94208)
announce url..: http://tracker.netbsd.org:6969/announce

You can use aria2.  From the aria2c(1) man page:

-S, --show-files[=true|false]

Print file listing of ".torrent", ".meta4" and ".metalink" file and exit. In case of ".torrent" file, additional information (infohash, piece length, etc) is also printed.

$ aria2c -S ubuntu-14.04.2-desktop-i386.iso.torrent 
>>> Printing the contents of file 'ubuntu-14.04.2-desktop-i386.iso.torrent'...
*** BitTorrent File Information ***
Comment: Ubuntu CD releases.ubuntu.com
Creation Date: Thu, 19 Feb 2015 22:17:32 GMT
Mode: single
Announce:
 http://torrent.ubuntu.com:6969/announce
 http://ipv6.torrent.ubuntu.com:6969/announce
Info Hash: 33678ec8b0dfb8a9061348c8af7194268c0b8310
Piece Length: 512KiB
The Number of Pieces: 2006
Total Length: 0.9GiB (1,051,721,728)
Name: ubuntu-14.04.2-desktop-i386.iso
Magnet URI: magnet:?xt=urn:btih:33678EC8B0DFB8A9061348C8AF7194268C0B8310&dn=ubuntu-14.04.2-desktop-i386.iso&tr=http%3A%2F%2Ftorrent.ubuntu.com%3A6969%2Fannounce&tr=http%3A%2F%2Fipv6.torrent.ubuntu.com%3A6969%2Fannounce
Files:
idx|path/length
===+===========================================================================
  1|./ubuntu-14.04.2-desktop-i386.iso
   |0.9GiB (1,051,721,728)
---+---------------------------------------------------------------------------