diff --git a/packages/multichain/src/middlewares/multichainMethodCallValidator.test.ts b/packages/multichain/src/middlewares/multichainMethodCallValidator.test.ts
new file mode 100644
index 0000000000..96b48f95f7
--- /dev/null
+++ b/packages/multichain/src/middlewares/multichainMethodCallValidator.test.ts
@@ -0,0 +1,67 @@
+import type {
+  MethodCallValidationError,
+  MethodCallValidatorNoSchemaError,
+} from './multichainMethodCallValidator';
+import { multichainMethodCallValidator } from './multichainMethodCallValidator';
+
+describe('multichainMethodCallValidator', () => {
+  it('should validate method calls with no params', async () => {
+    const errors = await multichainMethodCallValidator('wallet_getSession', {});
+    expect(errors).toBe(false);
+  });
+
+  it('should validate method calls with invalid params when required and return errors', async () => {
+    const errors = await multichainMethodCallValidator('wallet_createSession', {
+      requiredScopes: true,
+    });
+    expect(errors).toHaveLength(1);
+    expect((errors as MethodCallValidationError[])[0].message).toBe(
+      'requiredScopes is not of a type(s) object',
+    );
+  });
+
+  it('should have no errors when params are valid', async () => {
+    const errors = await multichainMethodCallValidator('wallet_createSession', {
+      requiredScopes: {
+        'eip155:1337': {
+          methods: ['eth_sendTransaction'],
+          notifications: [],
+        },
+      },
+      optionalScopes: {
+        'eip155:1337': {
+          methods: ['eth_sendTransaction'],
+          notifications: [],
+        },
+      },
+    });
+    expect(errors).toBe(false);
+  });
+
+  describe('invalid number of params', () => {
+    it('should validate method calls with invalid number of params when required and return errors', async () => {
+      const errors = await multichainMethodCallValidator(
+        'wallet_createSession',
+        {
+          chainId: 'eip155:1',
+          accountAddress: '0x0',
+          foo: 'bar',
+          baz: 'potato',
+        },
+      );
+      expect(errors).toHaveLength(1);
+      expect((errors as MethodCallValidationError[])[0].message).toBe(
+        'Invalid number of parameters.',
+      );
+      expect((errors as MethodCallValidatorNoSchemaError[])[0].expected).toBe(
+        3,
+      );
+      expect((errors as MethodCallValidationError[])[0].got).toStrictEqual({
+        chainId: 'eip155:1',
+        accountAddress: '0x0',
+        foo: 'bar',
+        baz: 'potato',
+      });
+    });
+  });
+});
diff --git a/packages/multichain/src/middlewares/multichainMethodCallValidator.ts b/packages/multichain/src/middlewares/multichainMethodCallValidator.ts
index cc075140e2..2cc07003dc 100644
--- a/packages/multichain/src/middlewares/multichainMethodCallValidator.ts
+++ b/packages/multichain/src/middlewares/multichainMethodCallValidator.ts
@@ -2,12 +2,7 @@ import { MultiChainOpenRPCDocument } from '@metamask/api-specs';
 import type { JsonRpcMiddleware } from '@metamask/json-rpc-engine';
 import { rpcErrors } from '@metamask/rpc-errors';
 import { isObject } from '@metamask/utils';
-import type {
-  Json,
-  JsonRpcError,
-  JsonRpcParams,
-  JsonRpcRequest,
-} from '@metamask/utils';
+import type { Json, JsonRpcParams } from '@metamask/utils';
 import type {
   ContentDescriptorObject,
   MethodObject,
@@ -18,35 +13,83 @@ import { makeCustomResolver } from '@open-rpc/schema-utils-js/build/parse-open-r
 import type { Schema, ValidationError } from 'jsonschema';
 import { Validator } from 'jsonschema';
 
+export type MethodCallValidationSchemaError = {
+  message: string;
+  param: string;
+  path: (string | number)[];
+  schema: string | Schema;
+  got: unknown;
+};
+
+export type MethodCallValidatorNoSchemaError = {
+  message: string;
+  expected?: Json;
+  got: unknown;
+};
+
+export type MethodCallValidationError =
+  | MethodCallValidationSchemaError
+  | MethodCallValidatorNoSchemaError;
+
 const transformError = (
   error: ValidationError,
   param: ContentDescriptorObject,
   got: unknown,
-) => {
+): MethodCallValidationError => {
   // if there is a path, add it to the message
   const message = `${param.name}${
     error.path.length > 0 ? `.${error.path.join('.')}` : ''
   } ${error.message}`;
 
   return {
-    code: -32602, // TODO: could be a different error code or not wrapped in json-rpc error, since this will also be wrapped in a -32602 invalid params error
     message,
-    data: {
-      param: param.name,
-      path: error.path,
-      schema: error.schema,
-      got,
-    },
+    param: param.name,
+    path: error.path,
+    schema: error.schema,
+    got,
   };
 };
 
+const checkForInvalidParams = (
+  params: JsonRpcParams | undefined,
+  paramsToCheck: ContentDescriptorObject[],
+) => {
+  const errors: MethodCallValidationError[] = [];
+  const numRequiredParams = (paramsToCheck as ContentDescriptorObject[]).filter(
+    (p) => p.required,
+  ).length;
+
+  let paramsLength = 0;
+  if (Array.isArray(params)) {
+    paramsLength = params.length;
+  } else if (isObject(params)) {
+    paramsLength = Object.keys(params).length;
+  }
+
+  if (numRequiredParams > paramsLength && numRequiredParams > 0) {
+    errors.push({
+      message: `Invalid number of parameters.`,
+      expected: numRequiredParams,
+      got: params,
+    });
+  } else if (paramsLength > paramsToCheck.length) {
+    errors.push({
+      message: `Invalid number of parameters.`,
+      expected: paramsToCheck.length,
+      got: params,
+    });
+  }
+
+  return errors;
+};
+
 const v = new Validator();
 
 const dereffedPromise = dereferenceDocument(
   MultiChainOpenRPCDocument as unknown as OpenrpcDocument,
   makeCustomResolver({}),
 );
-const multichainMethodCallValidator = async (
+export const multichainMethodCallValidator = async (
   method: string,
   params: JsonRpcParams | undefined,
 ) => {
@@ -54,9 +97,12 @@ const multichainMethodCallValidator = async (
   const methodToCheck = dereffed.methods.find(
     (m) => (m as unknown as ContentDescriptorObject).name === method,
   );
-  const errors: JsonRpcError[] = [];
+  const errors: MethodCallValidationError[] = [];
+
+  const paramsToCheck = (methodToCheck as unknown as MethodObject).params;
+
   // check each param and aggregate errors
-  (methodToCheck as unknown as MethodObject).params.forEach((param, i) => {
+  paramsToCheck.forEach((param, i) => {
     let paramToCheck: Json | undefined;
     const p = param as ContentDescriptorObject;
     if (isObject(params)) {
@@ -72,28 +118,43 @@ const multichainMethodCallValidator = async (
     if (result.errors) {
       errors.push(
         ...result.errors.map((e) => {
-          return transformError(e, p, paramToCheck) as JsonRpcError;
+          return transformError(e, p, paramToCheck);
         }),
       );
     }
   });
+
+  const invalidParamsErrors = checkForInvalidParams(
+    params,
+    paramsToCheck as ContentDescriptorObject[],
+  );
+
+  if (invalidParamsErrors.length > 0) {
+    errors.push(...invalidParamsErrors);
+  }
+
   if (errors.length > 0) {
     return errors;
   }
+
   // feels like this should return true to indicate that its valid but i'd rather check the falsy value since errors
   // would be an array and return true if it's empty
   return false;
 };
 
 export const multichainMethodCallValidatorMiddleware: JsonRpcMiddleware<
-  JsonRpcRequest,
+  JsonRpcParams,
   Json
 > = function (request, _response, next, end) {
   // eslint-disable-next-line @typescript-eslint/no-floating-promises
   multichainMethodCallValidator(request.method, request.params).then(
     (errors) => {
       if (errors) {
-        return end(rpcErrors.invalidParams<JsonRpcError[]>({ data: errors }));
+        return end(
+          rpcErrors.invalidParams({
+            data: errors as Json[],
+          }),
+        );
       }
       return next();
     },