roxygen-param

Flag @param documentation that does not match the documented function.

Four shapes are reported: a formal argument with no @param, a @param naming a nonexistent formal (often a rename that never reached the docs), a name documented twice, and a @param missing its name or description. Blocks that inherit or merge documentation (@inheritParams, @rdname, @describeIn, @template) are exempt from the coverage checks; duplicates are always reported.

y is undocumented and @param z matches nothing:

#' Add two numbers
#' @param x The first number.
#' @param z The other one.
#' @export
add <- function(x, y) x + y

warning: roxygen-param
 --> example.R:3:11
  |
3 | #' @param z The other one.
  |           ^ `@param z` does not match a formal argument of the documented function
  = help: Rename it to a formal argument or remove it.
warning: roxygen-param
 --> example.R:5:20
  |
5 | add <- function(x, y) x + y
  |                    ^ formal argument `y` is not documented with `@param`
  = help: Add `@param` for it (or `@inheritParams` a function that documents it).