diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 76f4a193..b94afed9 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,5 +1,5 @@
 {
-  "packages/toolbox-langchain": "0.5.8",
+  "packages/toolbox-langchain": "0.5.9",
   "packages/toolbox-core": "0.5.8",
   "packages/toolbox-llamaindex": "0.5.8",
   "packages/toolbox-adk": "0.5.8"
diff --git a/packages/toolbox-langchain/CHANGELOG.md b/packages/toolbox-langchain/CHANGELOG.md
index ff342311..c2d2b023 100644
--- a/packages/toolbox-langchain/CHANGELOG.md
+++ b/packages/toolbox-langchain/CHANGELOG.md
@@ -1,5 +1,12 @@
 # Changelog
 
+## [0.5.9](https://github.com/googleapis/mcp-toolbox-sdk-python/compare/toolbox-langchain-v0.5.8...toolbox-langchain-v0.5.9) (2026-02-09)
+
+
+### Features
+
+* Enable package-specific client identification for MCP ([#525](https://github.com/googleapis/mcp-toolbox-sdk-python/issues/525)) ([7ac0d3f](https://github.com/googleapis/mcp-toolbox-sdk-python/commit/7ac0d3f167af1e47c26a3f43bdb48f3fc0a92109))
+
 ## [0.5.8](https://github.com/googleapis/mcp-toolbox-sdk-python/compare/toolbox-langchain-v0.5.7...toolbox-langchain-v0.5.8) (2026-01-28)
 
 
diff --git a/packages/toolbox-langchain/pyproject.toml b/packages/toolbox-langchain/pyproject.toml
index 72a64d4b..8fb580bc 100644
--- a/packages/toolbox-langchain/pyproject.toml
+++ b/packages/toolbox-langchain/pyproject.toml
@@ -9,7 +9,7 @@ authors = [
     {name = "Google LLC", email = "googleapis-packages@google.com"}
 ]
 dependencies = [
-    "toolbox-core==0.5.8",              # x-release-please-version
+    "toolbox-core==0.5.9",              # x-release-please-version
     "langchain-core>=0.2.23,<2.0.0",
     "PyYAML>=6.0.1,<7.0.0",
     "pydantic>=2.7.0,<3.0.0",
diff --git a/packages/toolbox-langchain/src/toolbox_langchain/version.py b/packages/toolbox-langchain/src/toolbox_langchain/version.py
index 9e6eaa21..49a2ee39 100644
--- a/packages/toolbox-langchain/src/toolbox_langchain/version.py
+++ b/packages/toolbox-langchain/src/toolbox_langchain/version.py
@@ -12,4 +12,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-__version__ = "0.5.8"
+__version__ = "0.5.9"