If you add new MIBs to your system, say cisco MIBs with snmp-mibs-downloader (debian), you have to tell snimpy where to find them (/var/lib/mibs/cisco).
Using /etc/snmp.conf does not work, as snimpy uses libsmi, so you have to add the path to /etc/smi.conf or $HOME/.smirc, as documented in man smi_config.
It would be very useful to add this information in the documentation of snimpy, because it is not easy for a user to find this out.
If you add new MIBs to your system, say cisco MIBs with snmp-mibs-downloader (debian), you have to tell snimpy where to find them (/var/lib/mibs/cisco). Using /etc/snmp.conf does not work, as snimpy uses libsmi, so you have to add the path to /etc/smi.conf or $HOME/.smirc, as documented in man smi_config.
It would be very useful to add this information in the documentation of snimpy, because it is not easy for a user to find this out.