diff --git a/.changeset/quiet-cooks-join.md b/.changeset/quiet-cooks-join.md
new file mode 100644
index 0000000000..a5f39f2ab4
--- /dev/null
+++ b/.changeset/quiet-cooks-join.md
@@ -0,0 +1,6 @@
+---
+'@hyperlane-xyz/cli': minor
+'@hyperlane-xyz/sdk': minor
+---
+
+Add `EthJsonRpcBlockParameterTag` enum for validating reorgPeriod
diff --git a/typescript/cli/src/config/chain.ts b/typescript/cli/src/config/chain.ts
index d3279a2029..e710b6cf00 100644
--- a/typescript/cli/src/config/chain.ts
+++ b/typescript/cli/src/config/chain.ts
@@ -5,6 +5,7 @@ import { stringify as yamlStringify } from 'yaml';
 import {
   ChainMetadata,
   ChainMetadataSchema,
+  EthJsonRpcBlockParameterTag,
   ExplorerFamily,
   ZChainName,
 } from '@hyperlane-xyz/sdk';
@@ -168,9 +169,11 @@ async function addBlockOrGasConfig(metadata: ChainMetadata): Promise<void> {
 }
 
 async function addBlockConfig(metadata: ChainMetadata): Promise<void> {
-  const parseReorgPeriod = (value: string) => {
+  const parseReorgPeriod = (
+    value: string,
+  ): number | EthJsonRpcBlockParameterTag => {
     const parsed = parseInt(value, 10);
-    return isNaN(parsed) ? value : parsed;
+    return isNaN(parsed) ? (value as EthJsonRpcBlockParameterTag) : parsed;
   };
 
   const wantBlockConfig = await confirm({
@@ -184,10 +187,16 @@ async function addBlockConfig(metadata: ChainMetadata): Promise<void> {
     });
     const blockReorgPeriod = await input({
       message:
-        'Enter no. of blocks before a transaction has a near-zero chance of reverting (0-500) or block tag:',
-      validate: (value) =>
-        isNaN(parseInt(value)) ||
-        (parseInt(value) >= 0 && parseInt(value) <= 500),
+        'Enter no. of blocks before a transaction has a near-zero chance of reverting (0-500) or block tag (earliest, latest, safe, finalized, pending):',
+      validate: (value) => {
+        const parsedInt = parseInt(value, 10);
+        return (
+          Object.values(EthJsonRpcBlockParameterTag).includes(
+            value as EthJsonRpcBlockParameterTag,
+          ) ||
+          (!isNaN(parsedInt) && parsedInt >= 0 && parsedInt <= 500)
+        );
+      },
     });
     const blockTimeEstimate = await input({
       message: 'Enter the rough estimate of time per block in seconds (0-20):',
diff --git a/typescript/sdk/src/index.ts b/typescript/sdk/src/index.ts
index 415a11d269..e9bd31bb42 100644
--- a/typescript/sdk/src/index.ts
+++ b/typescript/sdk/src/index.ts
@@ -196,6 +196,7 @@ export {
 export {
   BlockExplorer,
   BlockExplorerSchema,
+  EthJsonRpcBlockParameterTag,
   ChainMetadata,
   ChainMetadataSchema,
   ChainMetadataSchemaObject,
diff --git a/typescript/sdk/src/metadata/chainMetadata.test.ts b/typescript/sdk/src/metadata/chainMetadata.test.ts
index 65a980f834..f38a59e46d 100644
--- a/typescript/sdk/src/metadata/chainMetadata.test.ts
+++ b/typescript/sdk/src/metadata/chainMetadata.test.ts
@@ -2,7 +2,11 @@ import { expect } from 'chai';
 
 import { ProtocolType } from '@hyperlane-xyz/utils';
 
-import { ChainMetadata, isValidChainMetadata } from './chainMetadataTypes.js';
+import {
+  ChainMetadata,
+  EthJsonRpcBlockParameterTag,
+  isValidChainMetadata,
+} from './chainMetadataTypes.js';
 
 const minimalSchema: ChainMetadata = {
   chainId: 5,
@@ -68,7 +72,7 @@ describe('ChainMetadataSchema', () => {
         ...minimalSchema,
         blocks: {
           confirmations: 1,
-          reorgPeriod: 'finalized',
+          reorgPeriod: EthJsonRpcBlockParameterTag.Finalized,
         },
       }),
     ).to.eq(true);
diff --git a/typescript/sdk/src/metadata/chainMetadataTypes.ts b/typescript/sdk/src/metadata/chainMetadataTypes.ts
index cf6c9bb54b..bf41cd4ac2 100644
--- a/typescript/sdk/src/metadata/chainMetadataTypes.ts
+++ b/typescript/sdk/src/metadata/chainMetadataTypes.ts
@@ -10,6 +10,14 @@ import { ChainMap } from '../types.js';
 
 import { ZChainName, ZNzUint, ZUint } from './customZodTypes.js';
 
+export enum EthJsonRpcBlockParameterTag {
+  Earliest = 'earliest',
+  Latest = 'latest',
+  Safe = 'safe',
+  Finalized = 'finalized',
+  Pending = 'pending',
+}
+
 export enum ExplorerFamily {
   Etherscan = 'etherscan',
   Blockscout = 'blockscout',