diff --git a/.changeset/sixty-cooks-bathe.md b/.changeset/sixty-cooks-bathe.md
new file mode 100644
index 000000000..c2194c6d0
--- /dev/null
+++ b/.changeset/sixty-cooks-bathe.md
@@ -0,0 +1,5 @@
+---
+'@modelcontextprotocol/client': patch
+---
+
+Add @cfworker/json-schema as a runtime dependency to fix ERR_MODULE_NOT_FOUND
diff --git a/packages/client/package.json b/packages/client/package.json
index 537804b73..acb041c41 100644
--- a/packages/client/package.json
+++ b/packages/client/package.json
@@ -79,6 +79,7 @@
         "client": "tsx scripts/cli.ts client"
     },
     "dependencies": {
+        "@cfworker/json-schema": "^4.0.3",
         "cross-spawn": "catalog:runtimeClientOnly",
         "eventsource": "catalog:runtimeClientOnly",
         "eventsource-parser": "catalog:runtimeClientOnly",
@@ -108,4 +109,4 @@
         "vitest": "catalog:devTools",
         "tsdown": "catalog:devTools"
     }
-}
+}
\ No newline at end of file
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index d4fc79982..1847d83a5 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -492,6 +492,9 @@ importers:
 
   packages/client:
     dependencies:
+      '@cfworker/json-schema':
+        specifier: ^4.0.3
+        version: 4.1.1
       cross-spawn:
         specifier: catalog:runtimeClientOnly
         version: 7.0.6
@@ -511,9 +514,6 @@ importers:
         specifier: catalog:runtimeShared
         version: 4.3.6
     devDependencies:
-      '@cfworker/json-schema':
-        specifier: catalog:runtimeShared
-        version: 4.1.1
       '@eslint/js':
         specifier: catalog:devTools
         version: 9.39.4