3 files changed, 6 insertions, 3 deletions

diff --git a/crates/mbe/src/subtree_source.rs b/crates/mbe/src/subtree_source.rs
index a05cab0f3..bde370fdb 100644
--- a/crates/mbe/src/subtree_source.rs
+++ b/crates/mbe/src/subtree_source.rs
@@ -1,4 +1,6 @@
-//! FIXME: write short doc here
+//! Our parser is generic over the source of tokens it parses.
+//!
+//! This module defines tokens sourced from declarative macros.
 
 use parser::{Token, TokenSource};
 use syntax::{lex_single_syntax_kind, SmolStr, SyntaxKind, SyntaxKind::*, T};
diff --git a/crates/mbe/src/syntax_bridge.rs b/crates/mbe/src/syntax_bridge.rs
index a7c8c13c6..b13168bd3 100644
--- a/crates/mbe/src/syntax_bridge.rs
+++ b/crates/mbe/src/syntax_bridge.rs
@@ -1,4 +1,4 @@
-//! FIXME: write short doc here
+//! Conversions between [`SyntaxNode`] and [`tt::TokenTree`].
 
 use parser::{FragmentKind, ParseError, TreeSink};
 use rustc_hash::FxHashMap;
diff --git a/crates/mbe/src/tt_iter.rs b/crates/mbe/src/tt_iter.rs
index 195b8cf30..99a8d250b 100644
--- a/crates/mbe/src/tt_iter.rs
+++ b/crates/mbe/src/tt_iter.rs
@@ -1,4 +1,5 @@
-//! FIXME: write short doc here
+//! A "Parser" structure for token trees. We use this when parsing a declarative
+//! macro definition into a list of patterns and templates.
 
 use crate::{subtree_source::SubtreeTokenSource, ExpandError, ExpandResult};