diff --git a/serverless/src/env.ts b/serverless/src/env.ts
index 4a115cc..7400070 100644
--- a/serverless/src/env.ts
+++ b/serverless/src/env.ts
@@ -238,7 +238,7 @@ export function getConfigFromCfnParams(params: CfnParams) {
   };
 }
 
-export function validateParameters(config: Configuration) {
+export function validateParameters(config: Configuration): string[] {
   log.debug("Validating parameters...");
   const errors: string[] = [];
 
@@ -278,7 +278,7 @@ export function validateParameters(config: Configuration) {
   return errors;
 }
 
-export function checkForMultipleApiKeys(config: Configuration) {
+export function checkForMultipleApiKeys(config: Configuration): string | undefined {
   let multipleApiKeysMessage;
   if (config.apiKey !== undefined && config.apiKMSKey !== undefined && config.apiKeySecretArn !== undefined) {
     multipleApiKeysMessage = "`apiKey`, `apiKMSKey`, and `apiKeySecretArn`";
@@ -293,7 +293,7 @@ export function checkForMultipleApiKeys(config: Configuration) {
   return multipleApiKeysMessage;
 }
 
-export function setEnvConfiguration(config: Configuration, lambdas: LambdaFunction[]) {
+export function setEnvConfiguration(config: Configuration, lambdas: LambdaFunction[]): void {
   lambdas.forEach((lambda) => {
     const environment = lambda.properties.Environment ?? {};
     const envVariables = environment.Variables ?? {};
diff --git a/serverless/src/forwarder.ts b/serverless/src/forwarder.ts
index 8f1f48a..f72af0f 100644
--- a/serverless/src/forwarder.ts
+++ b/serverless/src/forwarder.ts
@@ -77,7 +77,7 @@ export async function addCloudWatchForwarderSubscriptions(
   stackName: string | undefined,
   forwarderArn: string,
   cloudWatchLogs: CloudWatchLogs,
-) {
+): Promise<void> {
   let logGroupsOnStack: CloudWatchLogs.LogGroups | undefined;
   let logGroupsInTemplate: LogGroupDefinition[] | undefined;
   let subscriptionsInTemplate: SubscriptionDefinition[] | undefined;
@@ -203,7 +203,10 @@ export async function addCloudWatchForwarderSubscriptions(
   }
 }
 
-export async function findExistingLogGroupWithFunctionName(cloudWatchLogs: CloudWatchLogs, functionName: string) {
+export async function findExistingLogGroupWithFunctionName(
+  cloudWatchLogs: CloudWatchLogs,
+  functionName: string,
+): Promise<any> {
   const logGroupName = `${LAMBDA_LOG_GROUP_PREFIX}${functionName}`;
   const args = {
     logGroupNamePrefix: logGroupName,
@@ -216,7 +219,10 @@ export async function findExistingLogGroupWithFunctionName(cloudWatchLogs: Cloud
   return logGroups.find((lg) => lg.logGroupName === logGroupName);
 }
 
-export async function getExistingLambdaLogGroupsOnStack(cloudWatchLogs: CloudWatchLogs, stackName: string) {
+export async function getExistingLambdaLogGroupsOnStack(
+  cloudWatchLogs: CloudWatchLogs,
+  stackName: string,
+): Promise<any> {
   const logGroupNamePrefix = `${LAMBDA_LOG_GROUP_PREFIX}${stackName}-`;
   const args = { logGroupNamePrefix };
   const response = await cloudWatchLogs.describeLogGroups(args).promise();
@@ -225,7 +231,7 @@ export async function getExistingLambdaLogGroupsOnStack(cloudWatchLogs: CloudWat
   return logGroups ?? [];
 }
 
-export async function shouldSubscribeLogGroup(cloudWatchLogs: CloudWatchLogs, logGroupName: string) {
+export async function shouldSubscribeLogGroup(cloudWatchLogs: CloudWatchLogs, logGroupName: string): Promise<boolean> {
   const subscriptionFilters = await describeSubscriptionFilters(cloudWatchLogs, logGroupName);
   const numberOfActiveSubscriptionFilters = subscriptionFilters.length;
   if (numberOfActiveSubscriptionFilters >= MAX_ALLOWABLE_LOG_GROUP_SUBSCRIPTIONS) {
@@ -243,7 +249,7 @@ export async function shouldSubscribeLogGroup(cloudWatchLogs: CloudWatchLogs, lo
   return true;
 }
 
-async function describeSubscriptionFilters(cloudWatchLogs: CloudWatchLogs, logGroupName: string) {
+async function describeSubscriptionFilters(cloudWatchLogs: CloudWatchLogs, logGroupName: string): Promise<any> {
   const request = { logGroupName };
   const response = await cloudWatchLogs.describeSubscriptionFilters(request).promise();
   return response.subscriptionFilters ?? [];
@@ -257,7 +263,11 @@ function findLogGroupsInTemplate(resources: Resources) {
     });
 }
 
-export function findDeclaredLogGroup(logGroups: LogGroupDefinition[], functionKey: string, functionName?: string) {
+export function findDeclaredLogGroup(
+  logGroups: LogGroupDefinition[],
+  functionKey: string,
+  functionName?: string,
+): LogGroupDefinition | undefined {
   for (const resource of Object.values(logGroups)) {
     const logGroupName = resource.logGroupResource.Properties.LogGroupName;
 
@@ -298,7 +308,7 @@ function findDeclaredSub(
   subscriptions: SubscriptionDefinition[],
   logGroupName: string | { [fn: string]: any },
   logGroupKey: string,
-) {
+): SubscriptionDefinition | undefined {
   for (const subscription of subscriptions) {
     const subscribedLogGroupName = subscription.subscriptionResource.Properties.LogGroupName;
     if (typeof subscribedLogGroupName === "string" && subscribedLogGroupName.includes(logGroupKey)) {
@@ -310,7 +320,11 @@ function findDeclaredSub(
   }
 }
 
-async function putSubscriptionFilter(cloudWatchLogs: CloudWatchLogs, forwarderArn: string, logGroupName: string) {
+async function putSubscriptionFilter(
+  cloudWatchLogs: CloudWatchLogs,
+  forwarderArn: string,
+  logGroupName: string,
+): Promise<void> {
   const args = {
     destinationArn: forwarderArn,
     filterName: SUBSCRIPTION_FILTER_NAME,
@@ -320,7 +334,7 @@ async function putSubscriptionFilter(cloudWatchLogs: CloudWatchLogs, forwarderAr
   await cloudWatchLogs.putSubscriptionFilter(args).promise();
 }
 
-async function createLogGroup(cloudWatchLogs: CloudWatchLogs, logGroupName: string) {
+async function createLogGroup(cloudWatchLogs: CloudWatchLogs, logGroupName: string): Promise<void> {
   const args = { logGroupName };
   await cloudWatchLogs.createLogGroup(args).promise();
 }
diff --git a/serverless/src/git.ts b/serverless/src/git.ts
index 9bae9ce..b5195a1 100644
--- a/serverless/src/git.ts
+++ b/serverless/src/git.ts
@@ -1,4 +1,4 @@
-export const filterSensitiveInfoFromRepository = (repositoryUrl: string | undefined) => {
+export const filterSensitiveInfoFromRepository = (repositoryUrl: string | undefined): string | undefined => {
   try {
     if (!repositoryUrl) {
       return repositoryUrl;
diff --git a/serverless/src/index.ts b/serverless/src/index.ts
index 9208e18..23c4e88 100644
--- a/serverless/src/index.ts
+++ b/serverless/src/index.ts
@@ -213,7 +213,7 @@ export const handler = async (event: InputEvent, _: any) => {
  * the 'FunctionName' property. In this case, it means at least one of the names
  * will be dynamically generated.
  */
-function lambdaHasDynamicallyGeneratedName(lambdas: LambdaFunction[]) {
+function lambdaHasDynamicallyGeneratedName(lambdas: LambdaFunction[]): LambdaFunction[] {
   const dynmicallyNamedLambdas: LambdaFunction[] = [];
   for (const lambda of lambdas) {
     if (lambda.properties.FunctionName === undefined) {
@@ -223,7 +223,7 @@ function lambdaHasDynamicallyGeneratedName(lambdas: LambdaFunction[]) {
   return dynmicallyNamedLambdas;
 }
 
-export function getMissingStackNameErrorMsg(lambdaKeys: string[]) {
+export function getMissingStackNameErrorMsg(lambdaKeys: string[]): string {
   return (
     "A forwarder ARN was provided with one or more dynamically named lambda function resources," +
     " but the stack name was not provided. Without the stack name, the dynamically generated" +
diff --git a/serverless/src/layer.ts b/serverless/src/layer.ts
index 407c342..df0d6da 100644
--- a/serverless/src/layer.ts
+++ b/serverless/src/layer.ts
@@ -117,7 +117,7 @@ export const layerNameLookup: { [key in ArchitectureType]: { [key: string]: stri
  * Also assigns a general runtime type to the output lambdas. This helps to determine which lambda
  * layers to add & which handler to redirect to later on in the macro.
  */
-export function findLambdas(resources: Resources, templateParameterValues: Parameters) {
+export function findLambdas(resources: Resources, templateParameterValues: Parameters): LambdaFunction[] {
   return Object.entries(resources)
     .map(([key, resource]) => {
       if (resource.Type !== LAMBDA_FUNCTION_RESOURCE_TYPE) {
@@ -176,7 +176,7 @@ export function applyLayers(
   nodeLayerVersion?: number,
   dotnetLayerVersion?: number,
   javaLayerVersion?: number,
-) {
+): string[] {
   const errors: string[] = [];
   lambdas.forEach((lambda) => {
     if (lambda.runtimeType === RuntimeType.UNSUPPORTED) {
@@ -233,7 +233,11 @@ export function applyLayers(
   return errors;
 }
 
-export function applyExtensionLayer(region: string, lambdas: LambdaFunction[], extensionLayerVersion?: number) {
+export function applyExtensionLayer(
+  region: string,
+  lambdas: LambdaFunction[],
+  extensionLayerVersion?: number,
+): string[] {
   const errors: string[] = [];
   lambdas.forEach((lambda) => {
     let lambdaExtensionLayerArn;
@@ -250,7 +254,7 @@ export function applyExtensionLayer(region: string, lambdas: LambdaFunction[], e
   return errors;
 }
 
-function addLayer(layerArn: string, lambda: LambdaFunction) {
+function addLayer(layerArn: string, lambda: LambdaFunction): void {
   if (layerArn === undefined) {
     return;
   }
@@ -292,7 +296,12 @@ export function getNewLayers(layerArn: string, currentLayers: LambdaLayersProper
   return { [CFN_IF_FUNCTION_STRING]: [conditionalName, newLayersIfTrue, newLayersIfFalse] };
 }
 
-export function getLambdaLibraryLayerArn(region: string, version: number, runtime: string, architecture: string) {
+export function getLambdaLibraryLayerArn(
+  region: string,
+  version: number,
+  runtime: string,
+  architecture: string,
+): string {
   const layerName = layerNameLookup[architectureLookup[architecture]][runtime];
   const isGovCloud = region === "us-gov-east-1" || region === "us-gov-west-1";
 
@@ -304,7 +313,7 @@ export function getLambdaLibraryLayerArn(region: string, version: number, runtim
   return `arn:aws:lambda:${region}:${DD_ACCOUNT_ID}:layer:${layerName}:${version}`;
 }
 
-export function getExtensionLayerArn(region: string, version: number, architecture: string) {
+export function getExtensionLayerArn(region: string, version: number, architecture: string): string {
   const layerName = architectureToExtensionLayerName[architecture];
 
   const isGovCloud = region === "us-gov-east-1" || region === "us-gov-west-1";
@@ -317,14 +326,18 @@ export function getExtensionLayerArn(region: string, version: number, architectu
   return `arn:aws:lambda:${region}:${DD_ACCOUNT_ID}:layer:${layerName}:${version}`;
 }
 
-export function getMissingLayerVersionErrorMsg(functionKey: string, formalRuntime: string, paramRuntime: string) {
+export function getMissingLayerVersionErrorMsg(
+  functionKey: string,
+  formalRuntime: string,
+  paramRuntime: string,
+): string {
   return (
     `Resource ${functionKey} has a ${formalRuntime} runtime, but no ${formalRuntime} Lambda Library version was provided. ` +
     `Please add the '${paramRuntime}LayerVersion' parameter for the Datadog serverless macro.`
   );
 }
 
-export function getMissingExtensionLayerVersionErrorMsg(functionKey: string) {
+export function getMissingExtensionLayerVersionErrorMsg(functionKey: string): string {
   return (
     `Resource ${functionKey} has been configured to apply the extension laybe but no extension version was provided. ` +
     `Please add the 'extensionLayerVersion' parameter for the Datadog serverless macro`
diff --git a/serverless/src/redirect.ts b/serverless/src/redirect.ts
index e7d0d21..3950f02 100644
--- a/serverless/src/redirect.ts
+++ b/serverless/src/redirect.ts
@@ -13,7 +13,7 @@ export const JS_HANDLER = "node_modules/datadog-lambda-js/dist/handler.handler";
  * 'DD_LAMBDA_HANDLER' is set to the original handler in the lambda's environment for the
  * replacement handler to find.
  */
-export function redirectHandlers(lambdas: LambdaFunction[], addLayers: boolean) {
+export function redirectHandlers(lambdas: LambdaFunction[], addLayers: boolean): void {
   lambdas.forEach((lambda) => {
     if (lambda.runtimeType == RuntimeType.DOTNET || lambda.runtimeType == RuntimeType.JAVA) {
       setEnvDatadogWrapper(lambda);
@@ -41,7 +41,7 @@ function getDDHandler(lambdaRuntime: RuntimeType | undefined, addLayers: boolean
   }
 }
 
-function setEnvDatadogHandler(lambda: LambdaFunction) {
+function setEnvDatadogHandler(lambda: LambdaFunction): void {
   const environment = lambda.properties.Environment ?? {};
   const environmentVariables = environment.Variables ?? {};
 
@@ -52,7 +52,7 @@ function setEnvDatadogHandler(lambda: LambdaFunction) {
   lambda.properties.Environment = environment;
 }
 
-function setEnvDatadogWrapper(lambda: LambdaFunction) {
+function setEnvDatadogWrapper(lambda: LambdaFunction): void {
   const environment = lambda.properties.Environment ?? {};
   const environmentVariables = environment.Variables ?? {};
 
diff --git a/serverless/src/tags.ts b/serverless/src/tags.ts
index 4602cce..fe30319 100644
--- a/serverless/src/tags.ts
+++ b/serverless/src/tags.ts
@@ -8,7 +8,7 @@ const MACRO_VERSION = "dd_sls_macro";
 // Following the same pattern from SAM
 const MACRO_BY = "dd_sls_macro_by";
 
-export function addDDTags(lambdas: LambdaFunction[], config: Configuration) {
+export function addDDTags(lambdas: LambdaFunction[], config: Configuration): void {
   // Add the tags for each function, unless a tag already exists.
   lambdas.forEach((lambda) => {
     const tags = lambda.properties.Tags ?? [];
@@ -41,7 +41,7 @@ export function addDDTags(lambdas: LambdaFunction[], config: Configuration) {
   });
 }
 
-export function addMacroTag(lambdas: LambdaFunction[], version: string | undefined) {
+export function addMacroTag(lambdas: LambdaFunction[], version: string | undefined): void {
   if (!version) return;
 
   lambdas.forEach((lambda) => {
@@ -52,7 +52,7 @@ export function addMacroTag(lambdas: LambdaFunction[], version: string | undefin
   });
 }
 
-export function addCDKTag(lambdas: LambdaFunction[]) {
+export function addCDKTag(lambdas: LambdaFunction[]): void {
   lambdas.forEach((lambda) => {
     const tags = lambda.properties.Tags ?? [];
     tags.push({ Key: MACRO_BY, Value: "CDK" });
@@ -61,7 +61,7 @@ export function addCDKTag(lambdas: LambdaFunction[]) {
   });
 }
 
-export function addSAMTag(lambdas: LambdaFunction[]) {
+export function addSAMTag(lambdas: LambdaFunction[]): void {
   lambdas.forEach((lambda) => {
     const tags = lambda.properties.Tags ?? [];
 
diff --git a/serverless/src/tracing.ts b/serverless/src/tracing.ts
index 26a9576..778cb20 100644
--- a/serverless/src/tracing.ts
+++ b/serverless/src/tracing.ts
@@ -48,7 +48,7 @@ export enum TracingMode {
   NONE,
 }
 
-function findIamRole(resources: Resources, lambda: LambdaFunction) {
+function findIamRole(resources: Resources, lambda: LambdaFunction): IamRoleProperties | undefined {
   const role = lambda.properties.Role;
   let roleKey;
   if (typeof role !== "string") {
@@ -66,7 +66,7 @@ function findIamRole(resources: Resources, lambda: LambdaFunction) {
   }
 }
 
-export function getTracingMode(config: Configuration) {
+export function getTracingMode(config: Configuration): TracingMode {
   if (config.enableXrayTracing && config.enableDDTracing) {
     return TracingMode.HYBRID;
   } else if (config.enableDDTracing) {
@@ -77,7 +77,7 @@ export function getTracingMode(config: Configuration) {
   return TracingMode.NONE;
 }
 
-export function enableTracing(tracingMode: TracingMode, lambdas: LambdaFunction[], resources: Resources) {
+export function enableTracing(tracingMode: TracingMode, lambdas: LambdaFunction[], resources: Resources): void {
   if (tracingMode === TracingMode.XRAY || tracingMode === TracingMode.HYBRID) {
     log.debug("Enabling Xray tracing...");
     const xrayPolicies = {