diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 3b9e2aabe..7db9a9d17 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,6 +1,6 @@
 {
   "packages/toolbox-langchain": "1.3.0",
-  "packages/toolbox-core": "1.3.0",
+  "packages/toolbox-core": "1.3.1",
   "packages/toolbox-llamaindex": "0.8.0",
   "packages/toolbox-adk": "1.3.1"
 }
\ No newline at end of file
diff --git a/packages/toolbox-core/CHANGELOG.md b/packages/toolbox-core/CHANGELOG.md
index 770cc2dee..75123fa9a 100644
--- a/packages/toolbox-core/CHANGELOG.md
+++ b/packages/toolbox-core/CHANGELOG.md
@@ -1,5 +1,20 @@
 # Changelog
 
+## [1.3.1](https://github.com/googleapis/mcp-toolbox-sdk-python/compare/toolbox-core-v1.3.0...toolbox-core-v1.3.1) (2026-08-25)
+
+
+### Bug Fixes
+
+* **core:** clean up draft protocol alias and remove hardcoded server version fallback ([#773](https://github.com/googleapis/mcp-toolbox-sdk-python/issues/773)) ([7598805](https://github.com/googleapis/mcp-toolbox-sdk-python/commit/7598805f1df91edd2fdcb9bbc7c874b8c03f3939))
+* **core:** strict 1:1 vendor prefix reading based on protocol version ([#747](https://github.com/googleapis/mcp-toolbox-sdk-python/issues/747)) ([6d2f61d](https://github.com/googleapis/mcp-toolbox-sdk-python/commit/6d2f61d0147f4199fd3fca224b4ee3fbfefb4957))
+
+
+### Miscellaneous Chores
+
+* **deps:** bump aiohttp in /packages/toolbox-core ([#765](https://github.com/googleapis/mcp-toolbox-sdk-python/issues/765)) ([cfbd090](https://github.com/googleapis/mcp-toolbox-sdk-python/commit/cfbd090a789daedf89e65d98830bed1d3090b45c))
+* **deps:** update mcp toolbox server version in integration tests to v1.9.0 ([#770](https://github.com/googleapis/mcp-toolbox-sdk-python/issues/770)) ([fefc2c6](https://github.com/googleapis/mcp-toolbox-sdk-python/commit/fefc2c656ade41c8671c98103d4a03cb896c6bd3))
+* release 1.3.1 ([#759](https://github.com/googleapis/mcp-toolbox-sdk-python/issues/759)) ([4b9dd77](https://github.com/googleapis/mcp-toolbox-sdk-python/commit/4b9dd77bf752edaefc084894367cd3fab4cfb1be))
+
 ## [1.3.0](https://github.com/googleapis/mcp-toolbox-sdk-python/compare/toolbox-core-v1.2.0...toolbox-core-v1.3.0) (2026-07-28)
 
 
diff --git a/packages/toolbox-core/src/toolbox_core/version.py b/packages/toolbox-core/src/toolbox_core/version.py
index 4f78e99d5..18cb9bf0e 100644
--- a/packages/toolbox-core/src/toolbox_core/version.py
+++ b/packages/toolbox-core/src/toolbox_core/version.py
@@ -12,4 +12,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-__version__ = "1.3.0"
+__version__ = "1.3.1"