Suggestion

#include <a_samp>
#include <zcmd>

new bool:IsPlayerAFK[MAX_PLAYERS] = false;


#if defined FILTERSCRIPT

public OnFilterScriptInit()
{
   print("\n--------------------------------------");
   print(" Blank Filterscript by your name here");
   print("--------------------------------------\n");
   return 1;
}







public OnPlayerCommandText(playerid, cmdtext[])
{
   CMD:afk(playerid, params[])
{
    new pName[24], string[100];
    GetPlayerName(playerid, pName, sizeof(pName));
    if(IsPlayerAFK[playerid] == false)
    {
        IsPlayerAFK[playerid] = true;
        TogglePlayerControllable(playerid, false);
        format(string, sizeof(string), "[AFK]: %s [%d] is now AFK.");
        SendClientMessageToAll(-1, string);
    }
    else//Else they ARE afk when they type /afk.
    {
        IsPlayerAFK[playerid] = false;
        TogglePlayerControllable(playerid, true);
        format(string, sizeof(string), "[AFK]: %s [%d] is no longer AFK.");
        SendClientMessageToAll(-1, string);
    }
    return true;
}
   return 0;
}

#endif