diff --git a/util/gen-types/Cargo.toml b/util/gen-types/Cargo.toml
index 2104ffe8f7d..5bc2e8815db 100644
--- a/util/gen-types/Cargo.toml
+++ b/util/gen-types/Cargo.toml
@@ -16,11 +16,7 @@ default = ["std"]
 calc-hash = ["blake2b-ref"]
 check-data = []
 serialized-size = ["calc-hash"]
-std = [ 
-    "calc-hash",
-    "check-data", 
-    "serialized-size", 
-    "molecule/std", "ckb-fixed-hash", "numext-fixed-uint", "ckb-error", "ckb-occupied-capacity", "ckb-hash" ]
+std = ["calc-hash", "check-data", "serialized-size", "molecule/std", "ckb-fixed-hash", "numext-fixed-uint", "ckb-error", "ckb-occupied-capacity", "ckb-hash"]
 
 [dependencies]
 molecule = { version = "0.7.5", default-features = false }
diff --git a/util/gen-types/src/core/mod.rs b/util/gen-types/src/core/mod.rs
index d8cb2ed194f..e31ff0c4e7a 100644
--- a/util/gen-types/src/core/mod.rs
+++ b/util/gen-types/src/core/mod.rs
@@ -1,3 +1,5 @@
+//! The essential rust types for CKB contracts.
+
 #![allow(clippy::from_over_into)]
 
 #[cfg(feature = "std")]
@@ -7,8 +9,6 @@ pub use std_env::*;
 
 use crate::packed;
 
-pub(crate) type BlockNumber = u64;
-
 /// Specifies how the script `code_hash` is used to match the script code and how to run the code.
 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
 pub enum ScriptHashType {
diff --git a/util/gen-types/src/extension/shortcut.rs b/util/gen-types/src/extension/shortcut.rs
index 644ef55ff46..84bfe9e0afb 100644
--- a/util/gen-types/src/extension/shortcut.rs
+++ b/util/gen-types/src/extension/shortcut.rs
@@ -1,10 +1,6 @@
-use crate::{
-    bytes,
-    core::{self, BlockNumber},
-    generated::packed,
-    prelude::*,
-    vec::Vec,
-};
+use crate::{bytes, core, generated::packed, prelude::*, vec::Vec};
+
+type BlockNumber = u64;
 
 impl packed::Byte32 {
     /// Creates a new `Bytes32` whose bits are all zeros.
@@ -293,6 +289,7 @@ impl AsRef<[u8]> for packed::TransactionKey {
 }
 
 impl packed::HeaderDigest {
+    /// Checks if the `HeaderDigest` is the default value.
     pub fn is_default(&self) -> bool {
         let default = Self::default();
         self.as_slice() == default.as_slice()
diff --git a/util/gen-types/src/lib.rs b/util/gen-types/src/lib.rs
index b33637004fd..6fb919cab79 100644
--- a/util/gen-types/src/lib.rs
+++ b/util/gen-types/src/lib.rs
@@ -9,10 +9,11 @@ extern crate alloc;
 
 mod conversion;
 pub mod core;
-pub mod extension;
+mod extension;
 mod generated;
 pub mod prelude;
 pub use generated::packed;
+#[allow(missing_docs)]
 pub mod util;
 
 //re-exports
diff --git a/util/types/src/prelude.rs b/util/types/src/prelude.rs
index d8c59b2901f..f9c2a228b66 100644
--- a/util/types/src/prelude.rs
+++ b/util/types/src/prelude.rs
@@ -16,21 +16,33 @@ pub use ckb_gen_types::prelude::*;
 
 use std::collections::HashSet;
 
+/// Trait for converting types into `TransactionView`.
 pub trait IntoTransactionView {
+    /// Converts the implementing type into a `TransactionView`.
     fn into_view(self) -> TransactionView;
 }
 
+/// Trait for converting types into `HeaderView`.
 pub trait IntoHeaderView {
+    /// Converts the implementing type into a `HeaderView`.
     fn into_view(self) -> HeaderView;
 }
 
+/// Trait for converting types into `UncleBlockView`.
 pub trait IntoUncleBlockView {
+    /// Converts the implementing type into an `UncleBlockView`.
     fn into_view(self) -> UncleBlockView;
 }
 
+/// Trait for converting types into `BlockView`.
 pub trait IntoBlockView {
+    /// Converts the implementing type into a `BlockView` without resetting the header.
     fn into_view_without_reset_header(self) -> BlockView;
+
+    /// Converts the implementing type into a `BlockView`.
     fn into_view(self) -> BlockView;
+
+    /// Converts a packed block and associated data into a `BlockView`.
     fn block_into_view_internal(
         block: packed::Block,
         tx_hashes: Vec<packed::Byte32>,
@@ -38,33 +50,54 @@ pub trait IntoBlockView {
     ) -> BlockView;
 }
 
+/// Trait for obtaining an advanced builder for `BlockView`.
 pub trait AsBlockBuilder {
+    /// Creates a new advanced builder for `BlockView`.
     fn new_advanced_builder() -> BlockBuilder;
+
+    /// Gets an advanced builder from the implementing type.
     fn as_advanced_builder(&self) -> BlockBuilder;
 }
+
+/// Trait for obtaining an advanced builder for `TransactionView`.
 pub trait AsTransactionBuilder {
+    /// Gets an advanced builder for `TransactionView` from the implementing type.
     fn as_advanced_builder(&self) -> TransactionBuilder;
 }
 
+/// Trait for obtaining an advanced builder for `HeaderView`.
 pub trait AsHeaderBuilder {
+    /// Gets an advanced builder for `HeaderView` from the implementing type.
     fn as_advanced_builder(&self) -> HeaderBuilder;
 }
 
+/// Trait for calculating difficulty.
 pub trait Difficulty {
+    /// Calculates and returns the difficulty value as a `U256`.
     fn difficulty(&self) -> U256;
 }
 
+/// Trait for building a compact block from a `BlockView`.
 pub trait BuildCompactBlock {
+    /// Builds a compact block from a `BlockView` and a set of prefilled transaction indexes.
     fn build_from_block(
         block: &BlockView,
         prefilled_transactions_indexes: &HashSet<usize>,
     ) -> packed::CompactBlock;
+
+    /// Returns the short IDs of the transactions in the compact block.
     fn block_short_ids(&self) -> Vec<Option<packed::ProposalShortId>>;
+
+    /// Returns the indexes of the short IDs in the compact block.
     fn short_id_indexes(&self) -> Vec<usize>;
 }
 
+/// Trait for resetting the header of a packed block.
 pub trait ResetBlock {
+    /// Resets the header of the packed block.
     fn reset_header(self) -> packed::Block;
+
+    /// Resets the header of the packed block with given transaction hashes and witness hashes.
     fn reset_header_with_hashes(
         self,
         tx_hashes: &[packed::Byte32],
@@ -72,6 +105,8 @@ pub trait ResetBlock {
     ) -> packed::Block;
 }
 
+/// Trait for calculating the extra hash of a block.
 pub trait CalcExtraHash {
+    /// Calculates and returns the extra hash of the block as an `ExtraHashView`.
     fn calc_extra_hash(&self) -> ExtraHashView;
 }
diff --git a/util/types/src/utilities/merkle_mountain_range.rs b/util/types/src/utilities/merkle_mountain_range.rs
index 7085fd3b8ac..a6a58ff2302 100644
--- a/util/types/src/utilities/merkle_mountain_range.rs
+++ b/util/types/src/utilities/merkle_mountain_range.rs
@@ -58,7 +58,9 @@ impl core::HeaderView {
     }
 }
 
+/// Trait for representing a header digest.
 pub trait HeaderDigest {
+    /// Verify the header digest
     fn verify(&self) -> Result<(), String>;
 }