Add missing documentation for several functions

diff --git a/src/handler/lib/get_merkle_leaf_element.h b/src/handler/lib/get_merkle_leaf_element.h
index 7212fe7..fbe7935 100644
--- a/src/handler/lib/get_merkle_leaf_element.h
+++ b/src/handler/lib/get_merkle_leaf_element.h
@@ -4,7 +4,10 @@
 #include "dispatcher.h"
 
 /**
- * TODO: docs
+ * Retrieves the preimage of the leaf at `leaf_index` in the Merkle tree identified by
+ * `merkle_root` and `tree_size`, and stores it in `out_ptr`.
+ *
+ * Returns the length of the preimage on success, or a negative number on failure.
  */
 int call_get_merkle_leaf_element(dispatcher_context_t *dispatcher_context,
                                  const uint8_t merkle_root[static 32],
diff --git a/src/handler/lib/get_merkle_leaf_hash.h b/src/handler/lib/get_merkle_leaf_hash.h
index 6585e43..1bc1a2f 100644
--- a/src/handler/lib/get_merkle_leaf_hash.h
+++ b/src/handler/lib/get_merkle_leaf_hash.h
@@ -4,10 +4,14 @@
 #include "dispatcher.h"
 
 /**
- * TODO: docs
+ * Retrieves the hash of the leaf at `leaf_index` in the Merkle tree identified by `merkle_root`
+ * and `tree_size`, and verifies the proof returned by the host against `merkle_root`.
+ *
+ * On success, writes the 32-byte leaf hash to `out` and returns 0. Returns a negative value on
+ * failure.
  */
 int call_get_merkle_leaf_hash(dispatcher_context_t *dispatcher_context,
                               const uint8_t merkle_root[static 32],
                               uint32_t tree_size,
                               uint32_t leaf_index,
-                              uint8_t out[static 32]);
\ No newline at end of file
+                              uint8_t out[static 32]);
diff --git a/src/handler/lib/get_merkle_leaf_index.h b/src/handler/lib/get_merkle_leaf_index.h
index c14ea4e..e1afff1 100644
--- a/src/handler/lib/get_merkle_leaf_index.h
+++ b/src/handler/lib/get_merkle_leaf_index.h
@@ -4,9 +4,14 @@
 #include "dispatcher.h"
 
 /**
- * TODO: docs
+ * Retrieves the index of the leaf whose hash is `leaf_hash` in the Merkle tree identified by
+ * `root` and `size`.
+ *
+ * Returns the leaf index on success, or a negative value on failure. This function validates the
+ * index returned by the host by retrieving the leaf hash at that index and checking that it matches
+ * `leaf_hash`.
  */
 int call_get_merkle_leaf_index(dispatcher_context_t *dispatcher_context,
                                size_t size,
                                const uint8_t root[static 32],
-                               const uint8_t leaf_hash[static 32]);
\ No newline at end of file
+                               const uint8_t leaf_hash[static 32]);
diff --git a/src/handler/lib/get_merkleized_map.h b/src/handler/lib/get_merkleized_map.h
index c7ddc01..0672046 100644
--- a/src/handler/lib/get_merkleized_map.h
+++ b/src/handler/lib/get_merkleized_map.h
@@ -6,7 +6,12 @@
 #include "merkle.h"
 
 /**
- * TODO: docs
+ * Fetches the `index`-th element of a Merkle tree of merkleized maps, decodes it into `out_ptr`,
+ * and verifies that the keys in the tree are lexicographically sorted. If `callback` is not `NULL`,
+ * it is invoked once for each key element while checking the keys; `callback_state` is passed
+ * through unchanged.
+ *
+ * Returns 0 on success, or a negative number if the leaf cannot be fetched, decoded, or validated.
  */
 int call_get_merkleized_map_with_callback(dispatcher_context_t *dispatcher_context,
                                           void *callback_state,
diff --git a/src/handler/lib/get_merkleized_map_value_hash.h b/src/handler/lib/get_merkleized_map_value_hash.h
index b3b42b3..030207d 100644
--- a/src/handler/lib/get_merkleized_map_value_hash.h
+++ b/src/handler/lib/get_merkleized_map_value_hash.h
@@ -14,7 +14,7 @@
  * success.
  *
  * NOTE: this does _not_ check that the keys are lexicographically sorted; the sanity check needs to
- * be done before.\
+ * be done before.
  */
 int call_get_merkleized_map_value_hash(dispatcher_context_t *dispatcher_context,
                                        const merkleized_map_commitment_t *map,