diff --git a/apps/gateway/src/lib/create-request-for-openapi-operation.ts b/apps/gateway/src/lib/create-request-for-openapi-operation.ts
index cec05f73..4d47c907 100644
--- a/apps/gateway/src/lib/create-request-for-openapi-operation.ts
+++ b/apps/gateway/src/lib/create-request-for-openapi-operation.ts
@@ -50,9 +50,7 @@ export async function createRequestForOpenAPIOperation(
     assert(incomingRequestParamsRaw, 400, 'Invalid empty request body')
   }
 
-  // TODO: Validate incoming request params against the tool's input JSON schema
-  // TODO: we want to coerce data types to match the schema for booleans, dates, etc
-  // Currently, these will fail if given as body params, for instance, on the origin server.
+  // Validate incoming request params against the tool's input JSON schema.
   const incomingRequestParams = cfValidateJsonSchemaObject({
     schema: tool.inputSchema,
     data: incomingRequestParamsRaw,
@@ -95,18 +93,27 @@ export async function createRequestForOpenAPIOperation(
   if (bodyParams.length > 0) {
     body = JSON.stringify(
       Object.fromEntries(
-        bodyParams.map(([key]) => [key, incomingRequestParams[key]])
+        bodyParams
+          .map(([key]) => [key, incomingRequestParams[key]])
+          // Prune undefined values. We know these aren't required fields,
+          // because the incoming request params have already been validated
+          // against the tool's input schema.
+          .filter(([, value]) => value !== undefined)
       )
     )
 
     headers['content-type'] ??= 'application/json'
   } else if (formDataParams.length > 0) {
-    body = JSON.stringify(
-      Object.fromEntries(
-        formDataParams.map(([key]) => [key, incomingRequestParams[key]])
-      )
-    )
+    // TODO: Double-check FormData usage.
+    const formData = new FormData()
+    for (const [key] of formDataParams) {
+      const value = incomingRequestParams[key]
+      if (value !== undefined) {
+        formData.append(key, value)
+      }
+    }
 
+    body = formData.toString()
     headers['content-type'] ??= 'application/x-www-form-urlencoded'
   }
 
diff --git a/packages/openapi-utils/src/get-tools-from-openapi-spec.ts b/packages/openapi-utils/src/get-tools-from-openapi-spec.ts
index 8cfda9e5..d5f86b44 100644
--- a/packages/openapi-utils/src/get-tools-from-openapi-spec.ts
+++ b/packages/openapi-utils/src/get-tools-from-openapi-spec.ts
@@ -20,6 +20,7 @@ import { camelCase, mergeJsonSchemaObjects } from './utils'
 
 const jsonContentType = 'application/json'
 const multipartFormData = 'multipart/form-data'
+// const applicationFormUrlEncoded = 'application/x-www-form-urlencoded'
 
 const httpMethods = ['get', 'post', 'put', 'delete', 'patch', 'trace'] as const
 const paramSources = ['body', 'formData', 'header', 'path', 'query'] as const
@@ -41,20 +42,6 @@ export async function getToolsFromOpenAPISpec(
   const tools: Tool[] = []
   const toolToOperationMap: Record<string, OpenAPIToolOperation> = {}
 
-  const requestBodyJsonSchemaPaths = [
-    'requestBody',
-    'content',
-    jsonContentType,
-    'schema'
-  ]
-
-  const requestBodyFormDataJsonSchemaPaths = [
-    'requestBody',
-    'content',
-    multipartFormData,
-    'schema'
-  ]
-
   const operationResponsePaths = [
     ['responses', '200', 'content', jsonContentType, 'schema'],
     ['responses', '201', 'content', jsonContentType, 'schema']
@@ -62,8 +49,10 @@ export async function getToolsFromOpenAPISpec(
   ]
 
   const operationRequestPaths = [
-    requestBodyJsonSchemaPaths,
-    requestBodyFormDataJsonSchemaPaths
+    ['requestBody', 'content', jsonContentType, 'schema'],
+    ['requestBody', 'content', multipartFormData, 'schema']
+    // TODO: Support application/x-www-form-urlencoded bodies
+    // ['requestBody', 'content', applicationFormUrlEncoded, 'schema']
   ]
 
   const operationNames = new Set<string>()