diff --git a/contracts/HubPool.sol b/contracts/HubPool.sol
index 11431df48..effbd4cc8 100644
--- a/contracts/HubPool.sol
+++ b/contracts/HubPool.sol
@@ -481,6 +481,7 @@ contract HubPool is HubPoolInterface, Testable, Lockable, MultiCaller, Ownable {
      * and the caller, or "liquidity provider" earns a continuous fee for their credit that they are extending relayers.
      * @notice Caller will receive an LP token representing their share of this pool. The LP token's redemption value
      * increments from the time that they enter the pool to reflect their accrued fees.
+     * @notice The caller of this function must approve this contract to spend l1TokenAmount of l1Token.
      * @param l1Token Token to deposit into this contract.
      * @param l1TokenAmount Amount of liquidity to provide.
      */
@@ -588,6 +589,7 @@ contract HubPool is HubPoolInterface, Testable, Lockable, MultiCaller, Ownable {
      * called; moreover, this method can't be called again until all leafs are executed.
      * @param bundleEvaluationBlockNumbers should contain the latest block number for all chains, even if there are no
      * relays contained on some of them. The usage of this variable should be defined in an off chain UMIP.
+     * @notice The caller of this function must approve this contract to spend bondAmount of bondToken.
      * @param poolRebalanceLeafCount Number of leaves contained in pool rebalance root. Max is the number of whitelisted chains.
      * @param poolRebalanceRoot Pool rebalance root containing leaves that will send tokens from this contract to a SpokePool.
      * @param relayerRefundRoot Relayer refund root to publish to SpokePool where a data worker can execute leaves to
@@ -745,6 +747,7 @@ contract HubPool is HubPoolInterface, Testable, Lockable, MultiCaller, Ownable {
      * @notice Caller stakes a bond to dispute the current root bundle proposal assuming it has not passed liveness
      * yet. The proposal is deleted, allowing a follow-up proposal to be submitted, and the dispute is sent to the
      * optimistic oracle to be adjudicated. Can only be called within the liveness period of the current proposal.
+     * @notice The caller of this function must approve this contract to spend bondAmount of l1Token.
      */
     function disputeRootBundle() public nonReentrant zeroOptimisticOracleApproval {
         uint32 currentTime = uint32(getCurrentTime());
diff --git a/contracts/PolygonTokenBridger.sol b/contracts/PolygonTokenBridger.sol
index c8f3cbc3d..13ad42fce 100644
--- a/contracts/PolygonTokenBridger.sol
+++ b/contracts/PolygonTokenBridger.sol
@@ -52,6 +52,7 @@ contract PolygonTokenBridger is Lockable {
 
     /**
      * @notice Called by Polygon SpokePool to send tokens over bridge to contract with the same address as this.
+     * @notice The caller of this function must approve this contract to spend amount of token.
      * @param token Token to bridge.
      * @param amount Amount to bridge.
      * @param isWrappedMatic True if token is WMATIC.
diff --git a/contracts/SpokePool.sol b/contracts/SpokePool.sol
index 2c7a4b592..04507f955 100644
--- a/contracts/SpokePool.sol
+++ b/contracts/SpokePool.sol
@@ -710,12 +710,16 @@ abstract contract SpokePool is SpokePoolInterface, Testable, Lockable, MultiCall
         }
     }
 
-    // @notice Caller specifies the max amount of tokens to send to user. Based on this amount and the amount of the
-    // relay remaining (as stored in the relayFills mapping), pull the amount of tokens from the caller ancillaryData
-    // and send to the caller.
-    // @dev relayFills keeps track of pre-fee fill amounts as a convenience to relayers who want to specify round
-    // numbers for the maxTokensToSend parameter or convenient numbers like 100 (i.e. relayers who will fully
-    // fill any relay up to 100 tokens, and partial fill with 100 tokens for larger relays).
+    /**
+     * @notice Caller specifies the max amount of tokens to send to user. Based on this amount and the amount of the
+     * relay remaining (as stored in the relayFills mapping), pull the amount of tokens from the caller
+     * and send to the recipient.
+     * @dev relayFills keeps track of pre-fee fill amounts as a convenience to relayers who want to specify round
+     * numbers for the maxTokensToSend parameter or convenient numbers like 100 (i.e. relayers who will fully
+     * fill any relay up to 100 tokens, and partial fill with 100 tokens for larger relays).
+     * @dev Caller must approve this contract to transfer up to maxTokensToSend of the relayData.destinationToken.
+     * The amount to be sent might end up less if there is insufficient relay amount remaining to be sent.
+     */
     function _fillRelay(
         bytes32 relayHash,
         RelayData memory relayData,