1 files changed, 7 insertions, 1 deletions
diff --git a/packages/types/src/index.ts b/packages/types/src/index.ts
index 442fbb2d6..044aae3c8 100644
--- a/packages/types/src/index.ts
+++ b/packages/types/src/index.ts
@@ -1,7 +1,13 @@
 import { BigNumber } from 'bignumber.js';
 
+export type JSONRPCErrorCallback = (err: Error | null, result?: JSONRPCResponsePayload) => void;
+
+/**
+ * Do not create your own provider. Use an existing provider from a Web3 or ProviderEngine library
+ * Read more about Providers in the 0x wiki.
+ */
 export interface Provider {
-    sendAsync(payload: JSONRPCRequestPayload, callback: (err: Error, result: JSONRPCResponsePayload) => void): void;
+    sendAsync(payload: JSONRPCRequestPayload, callback: JSONRPCErrorCallback): void;
 }
 
 export type ContractAbi = AbiDefinition[];