chore: drop zod from peerDependencies (kept as direct dependency) (modelcontextprotocol#1824)

Co-authored-by: Konstantin Konstantinov <KKonstantinov@users.noreply.github.com>

Author: felixweinberger

.changeset/drop-zod-peer-dep.md

@@ -0,0 +1,9 @@
+---
+'@modelcontextprotocol/client': patch
+'@modelcontextprotocol/server': patch
+---
+
+Drop `zod` from `peerDependencies` (kept as direct dependency)
+
+Since Standard Schema support landed, `zod` is purely an internal runtime dependency used for protocol message parsing. User-facing schemas (`registerTool`, `registerPrompt`) accept any Standard Schema library. `zod` remains in `dependencies` and auto-installs; users no longer
+need to install it alongside the SDK.

README.md

@@ -39,7 +39,7 @@ This monorepo publishes split packages:
 - **`@modelcontextprotocol/server`**: build MCP servers
 - **`@modelcontextprotocol/client`**: build MCP clients
 
-Both packages have a **required peer dependency** on `zod` for schema validation. The SDK uses Zod v4.
+Tool and prompt schemas use [Standard Schema](https://standardschema.dev/) — bring Zod v4, Valibot, ArkType, or any compatible library.
 
 ### Middleware packages (optional)
 
@@ -56,21 +56,21 @@ They are intentionally thin adapters: they should not introduce new MCP function
 ### Server
 
 ```bash
-npm install @modelcontextprotocol/server zod
+npm install @modelcontextprotocol/server
 # or
-bun add @modelcontextprotocol/server zod
+bun add @modelcontextprotocol/server
 # or
-deno add npm:@modelcontextprotocol/server npm:zod
+deno add npm:@modelcontextprotocol/server
 ```
 
 ### Client
 
 ```bash
-npm install @modelcontextprotocol/client zod
+npm install @modelcontextprotocol/client
 # or
-bun add @modelcontextprotocol/client zod
+bun add @modelcontextprotocol/client
 # or
-deno add npm:@modelcontextprotocol/client npm:zod
+deno add npm:@modelcontextprotocol/client
 ```
 
 ### Optional middleware packages
@@ -157,7 +157,8 @@ The `docs:multi` script checks out both the `v1.x` and `main` branches via git w
 
 ## v1 (legacy) documentation and fixes
 
-If you are using the **v1** generation of the SDK, the **v1 API documentation** is available at [`https://ts.sdk.modelcontextprotocol.io/`](https://ts.sdk.modelcontextprotocol.io/). The v1 source code and any v1-specific fixes live on the long-lived [`v1.x` branch](https://github.com/modelcontextprotocol/typescript-sdk/tree/v1.x). V2 API docs are at [`/v2/`](https://ts.sdk.modelcontextprotocol.io/v2/).
+If you are using the **v1** generation of the SDK, the **v1 API documentation** is available at [`https://ts.sdk.modelcontextprotocol.io/`](https://ts.sdk.modelcontextprotocol.io/). The v1 source code and any v1-specific fixes live on the long-lived
+[`v1.x` branch](https://github.com/modelcontextprotocol/typescript-sdk/tree/v1.x). V2 API docs are at [`/v2/`](https://ts.sdk.modelcontextprotocol.io/v2/).
 
 ## Contributing
 

packages/client/package.json

@@ -68,15 +68,11 @@
         "zod": "catalog:runtimeShared"
     },
     "peerDependencies": {
-        "@cfworker/json-schema": "catalog:runtimeShared",
-        "zod": "catalog:runtimeShared"
+        "@cfworker/json-schema": "catalog:runtimeShared"
     },
     "peerDependenciesMeta": {
         "@cfworker/json-schema": {
             "optional": true
-        },
-        "zod": {
-            "optional": false
         }
     },
     "devDependencies": {

packages/server/package.json

@@ -63,15 +63,11 @@
         "zod": "catalog:runtimeShared"
     },
     "peerDependencies": {
-        "@cfworker/json-schema": "catalog:runtimeShared",
-        "zod": "catalog:runtimeShared"
+        "@cfworker/json-schema": "catalog:runtimeShared"
     },
     "peerDependenciesMeta": {
         "@cfworker/json-schema": {
             "optional": true
-        },
-        "zod": {
-            "optional": false
         }
     },
     "devDependencies": {