diff --git a/handler/handler_main.h b/handler/handler_main.h
index 1e78aa562d..af01dbe735 100644
--- a/handler/handler_main.h
+++ b/handler/handler_main.h
@@ -24,6 +24,8 @@ namespace crashpad {
 //! This is exposed so that `crashpad_handler` can be embedded into another
 //! binary, but called and used as if it were a standalone executable.
 //!
+//! \param[in] argc \a argc as passed to `main()`.
+//! \param[in] argv \a argv as passed to `main()`.
 //! \param[in] user_stream_sources An optional vector containing the
 //!     extensibility data sources to call on crash. Each time a minidump is
 //!     created, the sources are called in turn. Any streams returned are added
diff --git a/handler/mac/crash_report_exception_handler.h b/handler/mac/crash_report_exception_handler.h
index b878cfe479..cc314f1fc9 100644
--- a/handler/mac/crash_report_exception_handler.h
+++ b/handler/mac/crash_report_exception_handler.h
@@ -47,6 +47,10 @@ class CrashReportExceptionHandler : public UniversalMachExcServer::Interface {
   //!     To interoperate with Breakpad servers, the recommended practice is to
   //!     specify values for the `"prod"` and `"ver"` keys as process
   //!     annotations.
+  //! \param[in] user_stream_data_sources Data sources to be used to extend
+  //!     crash reports. For each crash report that is written, the data sources
+  //!     are called in turn. These data sources may contribute additional
+  //!     minidump streams. `nullptr` if not required.
   CrashReportExceptionHandler(
       CrashReportDatabase* database,
       CrashReportUploadThread* upload_thread,
diff --git a/handler/win/crash_report_exception_handler.h b/handler/win/crash_report_exception_handler.h
index 521ccd36d0..54dfa97190 100644
--- a/handler/win/crash_report_exception_handler.h
+++ b/handler/win/crash_report_exception_handler.h
@@ -48,6 +48,10 @@ class CrashReportExceptionHandler : public ExceptionHandlerServer::Delegate {
   //!     To interoperate with Breakpad servers, the recommended practice is to
   //!     specify values for the `"prod"` and `"ver"` keys as process
   //!     annotations.
+  //! \param[in] user_stream_data_sources Data sources to be used to extend
+  //!     crash reports. For each crash report that is written, the data sources
+  //!     are called in turn. These data sources may contribute additional
+  //!     minidump streams. `nullptr` if not required.
   CrashReportExceptionHandler(
       CrashReportDatabase* database,
       CrashReportUploadThread* upload_thread,