We have an internal tool I'm trying to generate completions for, and some of the option strings include things like:

--opt "device where name=<customerid>-foo" 

In this case, ZSH is unable to load the generated completions due to the < being unescaped. Outputting to a file and giving a quick replace of all instances of < with \< allowed this to work.

The second problem case is where options contain single quotes in the usage description for example, an option:

--opt "a "string" to use" 

causes the following ZSH error:
#> tool param:name:delete --
_tool.phar:181: bad set of key/value pairs for associative array
_tool.phar:181: bad set of key/value pairs for associative array
_tool.phar:181: bad set of key/value pairs for associative array

I believe the "'s also need escaped when the completions are rendered.