Fix pyright type errors for CreateMessageResult.content

The PR changed CreateMessageResult.content to be either a single content
block or a list. Code accessing .type and .text directly now needs to handle
both cases by checking isinstance(content, list) first.

Also add explicit dict[str, Any] type annotations to test data containing
nested empty dicts to satisfy pyright's type inference.

Author: felixweinberger

examples/servers/everything-server/mcp_everything_server/server.py

@@ -134,8 +134,9 @@ async def test_sampling(prompt: str, ctx: Context[ServerSession, None]) -> str:
             max_tokens=100,
         )
 
-        if result.content.type == "text":
-            model_response = result.content.text
+        content = result.content[0] if isinstance(result.content, list) else result.content
+        if content.type == "text":
+            model_response = content.text
         else:
             model_response = "No response"
 

examples/snippets/servers/sampling.py

@@ -20,6 +20,7 @@ async def generate_poem(topic: str, ctx: Context[ServerSession, None]) -> str:
         max_tokens=100,
     )
 
-    if result.content.type == "text":
-        return result.content.text
-    return str(result.content)
+    content = result.content[0] if isinstance(result.content, list) else result.content
+    if content.type == "text":
+        return content.text
+    return str(content)

tests/shared/test_streamable_http.py

@@ -210,7 +210,10 @@ async def handle_call_tool(name: str, args: dict[str, Any]) -> list[TextContent]
                 )
 
                 # Return the sampling result in the tool response
-                response = sampling_result.content.text if sampling_result.content.type == "text" else None
+                content = (
+                    sampling_result.content[0] if isinstance(sampling_result.content, list) else sampling_result.content
+                )
+                response = content.text if content.type == "text" else None
                 return [
                     TextContent(
                         type="text",
@@ -1239,7 +1242,12 @@ async def sampling_callback(
         nonlocal sampling_callback_invoked, captured_message_params
         sampling_callback_invoked = True
         captured_message_params = params
-        message_received = params.messages[0].content.text if params.messages[0].content.type == "text" else None
+        msg_content = (
+            params.messages[0].content[0]
+            if isinstance(params.messages[0].content, list)
+            else params.messages[0].content
+        )
+        message_received = msg_content.text if msg_content.type == "text" else None
 
         return types.CreateMessageResult(
             role="assistant",

tests/test_types.py

@@ -1,3 +1,5 @@
+from typing import Any
+
 import pytest
 
 from mcp.types import (
@@ -142,7 +144,7 @@ async def test_sampling_message_with_user_role():
     assert isinstance(user_msg.content, TextContent)
 
     # Test with array of content including tool result
-    multi_content_data = {
+    multi_content_data: dict[str, Any] = {
         "role": "user",
         "content": [
             {"type": "text", "text": "Here's the result:"},
@@ -173,7 +175,7 @@ async def test_sampling_message_with_assistant_role():
     assert isinstance(assistant_msg.content, ToolUseContent)
 
     # Test with array of mixed content
-    multi_content_data = {
+    multi_content_data: dict[str, Any] = {
         "role": "assistant",
         "content": [
             {"type": "text", "text": "Let me search for that..."},
@@ -195,7 +197,7 @@ async def test_sampling_message_backward_compatibility():
     assert isinstance(old_msg.content, TextContent)
 
     # New-style message with tool content
-    new_style_data = {
+    new_style_data: dict[str, Any] = {
         "role": "assistant",
         "content": {"type": "tool_use", "name": "test", "id": "call_1", "input": {}},
     }
@@ -204,7 +206,7 @@ async def test_sampling_message_backward_compatibility():
     assert isinstance(new_msg.content, ToolUseContent)
 
     # Array content
-    array_style_data = {
+    array_style_data: dict[str, Any] = {
         "role": "user",
         "content": [{"type": "text", "text": "Result:"}, {"type": "tool_result", "toolUseId": "call_1", "content": []}],
     }
@@ -256,7 +258,7 @@ async def test_create_message_result_with_tool_use():
 async def test_client_capabilities_with_sampling_tools():
     """Test ClientCapabilities with nested sampling capabilities for SEP-1577."""
     # New structured format
-    capabilities_data = {
+    capabilities_data: dict[str, Any] = {
         "sampling": {"tools": {}},
     }
     capabilities = ClientCapabilities.model_validate(capabilities_data)
@@ -265,7 +267,7 @@ async def test_client_capabilities_with_sampling_tools():
     assert capabilities.sampling.tools is not None
 
     # With both context and tools
-    full_capabilities_data = {"sampling": {"context": {}, "tools": {}}}
+    full_capabilities_data: dict[str, Any] = {"sampling": {"context": {}, "tools": {}}}
     full_caps = ClientCapabilities.model_validate(full_capabilities_data)
     assert isinstance(full_caps.sampling, SamplingCapability)
     assert full_caps.sampling.context is not None