diff --git a/src/MC/fix_atom_swap.h b/src/MC/fix_atom_swap.h
index 0ad11d500a..3960736e9c 100644
--- a/src/MC/fix_atom_swap.h
+++ b/src/MC/fix_atom_swap.h
@@ -105,19 +105,33 @@ E: Region ID for fix atom/swap does not exist
 
 Self-explanatory.
 
+E: Must specify at least 2 types in fix atom/swap command
+
+Self-explanatory.
+
+E: Need ntypes-1 delta_mu values in fix atom/swap command
+
+Self-explanatory.
+
+E: Only 2 types allowed when not using semi-grand in fix atom/swap command
+
+Self-explanatory.
+
+E: Delta_mu not allowed when not using semi-grand in fix atom/swap command
+
+Self-explanatory.
+
 E: Invalid atom type in fix atom/swap command
 
 The atom type specified in the atom/swap command does not exist.
 
-E: Illegal fix atom/swap gas mass <= 0
+E: All atoms of a swapped type must have the same charge.
 
-The computed mass of the designated atom type was less 
-than or equal to zero.
+Self-explanatory.
 
 E: Cannot do atom/swap on atoms in atom_modify first group
 
 This is a restriction due to the way atoms are organized in a list to
 enable the atom_modify first command.
 
-
 */
diff --git a/src/MC/fix_bond_break.h b/src/MC/fix_bond_break.h
index f104aef7b5..72fa27f55b 100755
--- a/src/MC/fix_bond_break.h
+++ b/src/MC/fix_bond_break.h
@@ -100,13 +100,14 @@ E: Cannot use fix bond/break with non-molecular systems
 Only systems with bonds that can be changed can be used.  Atom_style
 template does not qualify.
 
-E: Fix bond/break requires special_bonds = 0,1,1
+E: Cannot yet use fix bond/break with this improper style
 
-This is a restriction of the current fix bond/break implementation.
+This is a current restriction in LAMMPS.
 
-W: Broken bonds will not alter angles, dihedrals, or impropers
+E: Fix bond/break needs ghost atoms from further away
 
-See the doc page for fix bond/break for more info on this
-restriction.
+This is because the fix needs to walk bonds to a certain distance to
+acquire needed info, The comm_modify cutoff command can be used to
+extend the communication range.
 
 */
diff --git a/src/MC/fix_bond_create.cpp b/src/MC/fix_bond_create.cpp
index 9936729390..217f3171fb 100755
--- a/src/MC/fix_bond_create.cpp
+++ b/src/MC/fix_bond_create.cpp
@@ -606,7 +606,7 @@ void FixBondCreate::check_ghosts()
   int flagall;
   MPI_Allreduce(&flag,&flagall,1,MPI_INT,MPI_SUM,world);
   if (flagall) 
-    error->all(FLERR,"Fix3 bond/create needs ghost atoms from further away");
+    error->all(FLERR,"Fix bond/create needs ghost atoms from further away");
   lastcheck = update->ntimestep;
 }
 
diff --git a/src/MC/fix_bond_create.h b/src/MC/fix_bond_create.h
index dee4ffb344..88f37d1a9b 100755
--- a/src/MC/fix_bond_create.h
+++ b/src/MC/fix_bond_create.h
@@ -126,22 +126,27 @@ E: Fix bond/create cutoff is longer than pairwise cutoff
 This is not allowed because bond creation is done using the
 pairwise neighbor list.
 
-E: Fix bond/create requires special_bonds lj = 0,1,1
+E: Fix bond/create angle type is invalid
 
 Self-explanatory.
 
-E: Fix bond/create requires special_bonds coul = 0,1,1
+E: Fix bond/create dihedral type is invalid
 
 Self-explanatory.
 
-W: Created bonds will not create angles, dihedrals, or impropers
+E: Fix bond/create improper type is invalid
 
-See the doc page for fix bond/create for more info on this
-restriction.
+Self-explanatory.
 
-E: Could not count initial bonds in fix bond/create
+E: Cannot yet use fix bond/create with this improper style
 
-Could not find one of the atoms in a bond on this processor.
+This is a current restriction in LAMMPS.
+
+E: Fix bond/create needs ghost atoms from further away
+
+This is because the fix needs to walk bonds to a certain distance to
+acquire needed info, The comm_modify cutoff command can be used to
+extend the communication range.
 
 E: New bond exceeded bonds per atom in fix bond/create
 
@@ -153,4 +158,16 @@ E: New bond exceeded special list size in fix bond/create
 See the special_bonds extra command for info on how to leave space in
 the special bonds list to allow for additional bonds to be formed.
 
+E: Fix bond/create induced too many angles/dihedrals/impropers per atom
+
+See the read_data command for info on setting the "extra angle per
+atom", etc header values to allow for additional angles, etc to be
+formed.
+
+E: Special list size exceeded in fix bond/create
+
+See the read_data command for info on setting the "extra special per
+atom" header value to allow for additional special values to be
+stored.
+
 */
diff --git a/src/MC/fix_gcmc.h b/src/MC/fix_gcmc.h
index cc5a62a11a..60712abeb7 100644
--- a/src/MC/fix_gcmc.h
+++ b/src/MC/fix_gcmc.h
@@ -154,10 +154,42 @@ E: Fix gcmc region extends outside simulation box
 
 Self-explanatory.
 
+E: Fix gcmc molecule must have coordinates
+
+UNDOCUMENTED
+
+E: Fix gcmc molecule must have atom types
+
+UNDOCUMENTED
+
+E: Invalid atom type in fix gcmc mol command
+
+Self-explanatory.
+
+E: Fix gcmc molecule template ID must be same as atom_style template ID
+
+UNDOCUMENTED
+
+E: Cannot use fix gcmc shake and not molecule
+
+UNDOCUMENTED
+
+E: Molecule template ID for fix gcmc does not exist
+
+UNDOCUMENTED
+
+W: Molecule template for fix gcmc has multiple molecules
+
+UNDOCUMENTED
+
 E: Region ID for fix gcmc does not exist
 
 Self-explanatory.
 
+W: fix gcmc using full_energy option
+
+UNDOCUMENTED
+
 E: Invalid atom type in fix gcmc command
 
 The atom type specified in the GCMC command does not exist.
@@ -181,11 +213,23 @@ Should not choose the GCMC molecule feature if no molecules are being
 simulated. The general molecule flag is off, but GCMC's molecule flag
 is on.
 
+E: Fix gcmc shake fix does not exist
+
+Self-explanatory.
+
+E: Fix gcmc and fix shake not using same molecule template ID
+
+Self-explanatory.
+
 E: Cannot use fix gcmc in a 2d simulation
 
 Fix gcmc is set up to run in 3d only. No 2d simulations with fix gcmc
 are allowed.
 
+E: Could not find fix gcmc exclusion group ID
+
+Self-explanatory.
+
 E: Could not find fix gcmc rotation group ID
 
 Self-explanatory.
@@ -204,14 +248,12 @@ E: Fix gcmc ran out of available molecule IDs
 
 See the setting for tagint in the src/lmptype.h file.
 
-E: Fix gcmc could not find any atoms in the user-supplied template molecule
+E: Fix gcmc ran out of available atom IDs
 
-When using the molecule option with fix gcmc, the user must supply a 
-template molecule in the usual LAMMPS data file with its molecule id
-specified in the fix gcmc command as the "type" of the exchanged gas.
+UNDOCUMENTED
 
-E: Fix gcmc incorrect number of atoms per molecule
+E: Too many total atoms
 
-The number of atoms in each gas molecule was not computed correctly.
+UNDOCUMENTED
 
 */
diff --git a/src/MC/fix_tfmc.h b/src/MC/fix_tfmc.h
index 43910d63a8..fee3a944cd 100755
--- a/src/MC/fix_tfmc.h
+++ b/src/MC/fix_tfmc.h
@@ -57,11 +57,11 @@ Self-explanatory.  Check the input script syntax and compare to the
 documentation for the command.  You can use -echo screen as a
 command-line option when running LAMMPS to see the offending line.
 
-E: fix tfmc displacement length must be > 0
+E: Fix tfmc displacement length must be > 0
 
-Self-explanatory. You can only enter strictly positive displacement lengths.
+Self-explanatory.
 
-E: Fix tfmc temperature must be > 0"
+E: Fix tfmc temperature must be > 0
 
 Self-explanatory.
 
@@ -69,4 +69,8 @@ E: Illegal fix tfmc random seed
 
 Seeds can only be nonzero positive integers.
 
+E: Fix tfmc is not compatible with fix shake
+
+These two commands cannot currently be used together.
+
 */