Sync open source content 🐝 (from b96cd652635deca50236d002f64a8af256f43a6d)

beezythebot · beezythebot · commit ae7801a80f9b · 2025-06-23T14:46:19.000Z
diff --git a/mcp/release-notes.mdx b/mcp/release-notes.mdx
@@ -3,7 +3,7 @@ title: MCP release notes
 description: A comparative guide to the major changes in the Model Context Protocol (MCP) across versions.
 ---
 
-import { Callout } from "@/mdx/components";
+import { Callout, Table } from "@/mdx/components";
 
 # MCP release notes
 
@@ -25,22 +25,184 @@ Each release of the Model Context Protocol (MCP) introduces changes to how LLM a
 
 ## MCP version history
 
-This section summarizes the significant differences between the **2025-03-26** release and the previous **2024-11-05** specification. The following table summarizes major changes between MCP versions.
+This section summarizes the significant differences between MCP versions. The following table summarizes major changes between MCP versions.
+
+<Table
+  data={[
+    {
+      fieldName:
+        "**[2025-06-18](https://github.com/modelcontextprotocol/modelcontextprotocol/releases/tag/2025-06-18)**",
+      type: "`Jun 18, 2025`",
+      required: "`Yes`",
+      description:
+        "- Removes [JSON-RPC batching](https://www.jsonrpc.org/specification#batch) (reversal from 2025-03-26)\n" +
+        "- Adds [structured tool output](https://modelcontextprotocol.io/specification/2025-06-18/server/tools#structured-content)\n" +
+        "- Classifies MCP servers as [OAuth Resource Servers](https://modelcontextprotocol.io/specification/2025-06-18/basic/authorization#authorization-server-discovery)\n" +
+        "- Requires [Resource Indicators](https://www.rfc-editor.org/rfc/rfc8707.html) for enhanced security\n" +
+        "- Adds [elicitation](https://modelcontextprotocol.io/specification/2025-06-18/client/elicitation) for server-initiated user requests\n" +
+        "- Adds [resource links](https://modelcontextprotocol.io/specification/2025-06-18/server/tools#resource-links) in tool results\n" +
+        "- Requires MCP-Protocol-Version header for HTTP requests",
+    },
+    {
+      fieldName:
+        "**[2025-03-26](https://github.com/modelcontextprotocol/modelcontextprotocol/releases/tag/2025-03-26)**",
+      type: "`Mar 26, 2025`",
+      required: "`Yes`",
+      description:
+        "- Adds structured [OAuth 2.1-style authorization](https://modelcontextprotocol.io/specification/2025-03-26/basic/authorization)\n" +
+        "- Replaces SSE with [Streamable HTTP](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#streamable-http)\n" +
+        "- Adds [JSON-RPC batching](https://www.jsonrpc.org/specification#batch) (later removed in 2025-06-18)\n" +
+        "- Introduces tool annotations (for example, read-only, destructive)\n" +
+        "- Adds support for audio content, progress messages, and completions capability",
+    },
+    {
+      fieldName:
+        "**[2024-11-05](https://github.com/modelcontextprotocol/modelcontextprotocol/releases/tag/2024-11-05)**",
+      type: "`Jan 17, 2025`",
+      required: "`—`",
+      description:
+        "- Initial schema stabilization\n" +
+        "- Defines core architecture and message format\n" +
+        "- Introduces tool, resource, and prompt concepts\n" +
+        "- Adds ProgressNotification and sampling features\n" +
+        "- Uses HTTP with SSE for streaming transport",
+    },
+  ]}
+  columns={[
+    { key: "fieldName", header: "Version" },
+    { key: "type", header: "Release date" },
+    { key: "description", header: "Changes" },
+    { key: "required", header: "Breaking changes" },
+  ]}
+/>
+
+## MCP 2025-06-18 vs MCP 2025-03-26
+
+The **2025-06-18** MCP release represents a significant refinement of the Model Context Protocol, introducing structured tool outputs, enhanced OAuth security, and server-initiated user interactions. However, it also removes JSON-RPC batching from the previous version, simplifying protocol implementation while adding new capabilities for better security and data handling.
 
-| **Version**                                                                                            | **Release date** | **Changes**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | **Breaking changes** |
-| ------------------------------------------------------------------------------------------------------ | ---------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------- |
-| **[2025-03-26](https://github.com/modelcontextprotocol/modelcontextprotocol/releases/tag/2025-03-26)** | Mar 26, 2025     | - Adds structured [OAuth 2.1-style authorization](https://modelcontextprotocol.io/specification/2025-03-26/basic/authorization)<br/>- Replaces SSE with [Streamable HTTP](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#streamable-http)<br/>- Adds [JSON-RPC batching](https://www.jsonrpc.org/specification#batch)<br/>- Introduces tool annotations (for example, `read-only`, `destructive`)<br/>- Adds support for audio content, progress messages, and completions capability | Yes                  |
-| **[2024-11-05](https://github.com/modelcontextprotocol/modelcontextprotocol/releases/tag/2024-11-05)** | Jan 17, 2025     | - Initial schema stabilization<br/>- Defines core architecture and message format<br/>- Introduces tool, resource, and prompt concepts<br/>- Adds `ProgressNotification` and sampling features<br/>- Uses HTTP with SSE for streaming transport                                                                                                                                                                                                                                                                  | —                    |
+Key highlights include:
+
+- **Removal of JSON-RPC batching:** The batching feature introduced in 2025-03-26 has been removed, simplifying the protocol implementation
+- **Structured tool output:** Tools can now return structured, predictable data formats for better integration
+- **Enhanced OAuth security:** MCP servers are now classified as OAuth Resource Servers with additional security requirements
+- **Elicitation capability:** Servers can now request additional information from users during interactions
+- **Resource links:** Tool results can now reference MCP resources, creating better integration between tools and data
+
+You may choose to remain on the **2025-03-26** version if you need:
+
+- **JSON-RPC batching support:** If your implementation relies on batching multiple requests
+- **Simpler OAuth implementation:** The earlier version has less stringent OAuth requirements
+
+## What's new in MCP 2025-06-18?
+
+MCP **2025-06-18** introduces structured tool outputs, removes JSON-RPC batching, enhances OAuth security with Resource Server requirements, and adds elicitation for server-initiated user requests. Here's a detailed breakdown of the major updates:
+
+### Removal of JSON-RPC Batching
+
+One of the most significant changes is the **removal of JSON-RPC batching** support, which was introduced in 2025-03-26. This decision simplifies the protocol implementation and reduces complexity for both clients and servers. The maintainers mentioned that there was ['no compelling use case for batching'](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/416), but not all users agreed.
+
+<Callout title="Note" type="info">
+  If you were using batching in your 2025-03-26 implementation, you'll need to
+  refactor to send individual requests instead of batched ones.
+</Callout>
+
+### Structured Tool Output
+
+The new [structured tool output](https://modelcontextprotocol.io/specification/2025-06-18/server/tools#structured-content) capability allows tools to return data in predictable, structured formats rather than just plain text responses.
+
+```python
+@app.tool("get_user_info", description="Get structured user information")
+async def get_user_info(user_id: str):
+    return {
+        "content": [{
+            "type": "structured",
+            "data": {
+                "user": {
+                    "id": user_id,
+                    "name": "John Doe",
+                    "email": "john@example.com",
+                    "status": "active"
+                }
+            },
+            "schema": {
+                "type": "object",
+                "properties": {
+                    "user": {
+                        "type": "object",
+                        "properties": {
+                            "id": {"type": "string"},
+                            "name": {"type": "string"},
+                            "email": {"type": "string"},
+                            "status": {"type": "string"}
+                        }
+                    }
+                }
+            }
+        }]
+    }
+```
+
+### Enhanced OAuth Security
+
+MCP servers are now classified as [OAuth Resource Servers](https://modelcontextprotocol.io/specification/2025-06-18/basic/authorization#authorization-server-discovery):
+
+1. **Resource Server Discovery:** Servers must provide metadata to help clients discover the corresponding Authorization Server
+2. **Resource Indicators:** Clients must implement [RFC 8707](https://www.rfc-editor.org/rfc/rfc8707.html) Resource Indicators to prevent malicious servers from obtaining inappropriate access tokens
+3. **Enhanced Security Guidelines:** New [security best practices](https://modelcontextprotocol.io/specification/2025-06-18/basic/security_best_practices) documentation
+
+### MCP Elicitation Support
+
+The new [elicitation](https://modelcontextprotocol.io/specification/2025-06-18/client/elicitation) capability enables servers to request additional information from users during interactions, making conversations more dynamic and context-aware.
+
+```python
+async def handle_complex_query(query: str, context):
+    if missing_context(query):
+        # Request additional information from user
+        additional_info = await context.elicit_user_input(
+            prompt="I need more details about your requirements. What specific format would you like the output in?",
+            options=["JSON", "CSV", "Plain text"]
+        )
+        # Process with additional context
+        return process_with_context(query, additional_info)
+```
+
+### Resource Links in Tool Results
+
+Tools can now return [resource links](https://modelcontextprotocol.io/specification/2025-06-18/server/tools#resource-links) that reference MCP resources, creating better integration between tool outputs and available data sources.
+
+### MCP Protocol Version Headers
+
+HTTP requests now require the `MCP-Protocol-Version` header to enable [version negotiation](https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#protocol-version-header):
+
+```http
+POST /mcp HTTP/1.1
+Host: example.com
+Content-Type: application/json
+MCP-Protocol-Version: 2025-06-18
+
+{
+  "jsonrpc": "2.0",
+  "method": "tools/call",
+  "params": { ... }
+}
+```
+
+### Other Notable Changes in MCP 2025-06-18
+
+- **Lifecycle Operations:** Changed from **SHOULD** to **MUST** for certain [lifecycle operations](https://modelcontextprotocol.io/specification/2025-06-18/basic/lifecycle#operation)
+- **Meta Fields:** Added `_meta` field to additional interface types for better extensibility
+- **Completion Context:** Added `context` field to `CompletionRequest` for LLM-based autocompletion support
+- **Title Fields:** Added `title` field for human-friendly display names while keeping `name` as programmatic identifier
 
-## 2025-03-26 vs 2024-11-05
+## MCP 2025-03-26 vs MCP 2024-11-05
 
 The **2025-03-26** release of the Model Context Protocol introduces a more mature and standardized approach to authorization, transport, and tool metadata. It brings significant improvements in security, flexibility, and client compatibility, but it also includes breaking changes that may require updates in existing implementations if you are moving from the **2024-11-05** version.
 
 Key highlights include:
 
 - **Structured OAuth-style authorization:** Authorization is now defined explicitly using a consistent schema, making supporting various auth models and token types easier.
 - **Streamable HTTP transport:** The previous HTTP with SSE model has been replaced with a more robust, proxy-friendly HTTP streaming format.
-- **JSON-RPC batching:** Developers can now bundle multiple requests in a single call, improving efficiency in complex workflows.
+- **JSON-RPC batching:** Developers can now bundle multiple requests in a single call, improving efficiency in complex workflows (note: this was later removed in 2025-06-18).
 - **Tool annotations:** Tools can now describe their behavior (for example, `read-only`, `destructive`), allowing for safer and more user-aware execution.
 
 You may choose to remain on the **2024-11-05** version if you need:
@@ -168,7 +330,7 @@ Here are some reasons you should consider switching to Streamable HTTP:
 
 Apart from the improvements to authorization and HTTP streaming transport, MCP **2025-03-26** introduces these changes:
 
-- **Tool calls can now be batched:** Clients may send multiple tool invocations in a single JSON-RPC request. Servers that assume one call per request must handle arrays and concurrent execution.
+- **Tool calls can now be batched:** Clients may send multiple tool invocations in a single JSON-RPC request. Servers that assume one call per request must handle arrays and concurrent execution. (Note: This feature was removed in 2025-06-18)
 - **Tool behavior must now be declared explicitly:** Tools can define attributes like `readOnly` or `destructive`, which clients are expected to respect. This may impact how tools are displayed or gated in UIs.
 - **Progress updates are now more descriptive:** The `ProgressNotification` object includes an optional `message` field. Clients that display progress may want to surface these descriptions to users.
 - **Audio is a supported content type:** Servers and clients must now handle `audio` in addition to `text` and `image`.
