From 1da1eb581a58b1b7cdddd49e39a29ca9e9b83ea3 Mon Sep 17 00:00:00 2001
From: Tapan Chugh <chugh.tapan@gmail.com>
Date: Tue, 22 Jul 2025 05:08:39 -0700
Subject: [PATCH] Skip repeated type conversion and validation in proxy client
 elicitation handler (#1222)

Co-authored-by: Tapan Chugh <tapanc@cs.washington.edu>
---
 src/fastmcp/server/proxy.py             | 11 +++---
 tests/server/proxy/test_proxy_client.py | 45 +++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/src/fastmcp/server/proxy.py b/src/fastmcp/server/proxy.py
index cfd8ba57a..ebcb0f80e 100644
--- a/src/fastmcp/server/proxy.py
+++ b/src/fastmcp/server/proxy.py
@@ -566,11 +566,12 @@ class ProxyClient(Client[ClientTransportT]):
         A handler that forwards the elicitation request from the remote server to the proxy's connected clients and relays the response back to the remote server.
         """
         ctx = get_context()
-        result = await ctx.elicit(message, response_type)
-        if result.action == "accept":
-            return result.data
-        else:
-            return ElicitResult(action=result.action)
+        result = await ctx.session.elicit(
+            message=message,
+            requestedSchema=params.requestedSchema,
+            related_request_id=ctx.request_id,
+        )
+        return ElicitResult(action=result.action, content=result.content)
 
     @classmethod
     async def default_log_handler(cls, message: LogMessage) -> None:
diff --git a/tests/server/proxy/test_proxy_client.py b/tests/server/proxy/test_proxy_client.py
index ffd17116f..6239a9e85 100644
--- a/tests/server/proxy/test_proxy_client.py
+++ b/tests/server/proxy/test_proxy_client.py
@@ -4,6 +4,7 @@ from typing import cast
 import pytest
 from anyio import create_task_group
 from mcp.types import LoggingLevel, ModelHint, ModelPreferences, TextContent
+from pydantic import BaseModel, Field
 
 from fastmcp import Client, Context, FastMCP
 from fastmcp.client.elicitation import ElicitRequestParams, ElicitResult
@@ -330,6 +331,50 @@ class TestProxyClient:
         assert results["elicitation_a"] == "Hello, Alice!"
         assert results["elicitation_b"] == "Hello, Bob!"
 
+    async def test_elicit_with_default_values(self, fastmcp_server: FastMCP):
+        """
+        Test that the proxy client correctly handles elicitation with default values (fixes #1167).
+        """
+
+        @fastmcp_server.tool
+        async def elicit_with_defaults(context: Context) -> str:
+            class TestModel(BaseModel):
+                content: str = Field(description="Your reply content")
+                acknowledge: bool = Field(
+                    default=False, description="Send immediately or save as draft"
+                )
+
+            result = await context.elicit(
+                "Please provide input:", response_type=TestModel
+            )
+
+            if result.action == "accept":
+                return f"Content: {result.data.content}, Acknowledge: {result.data.acknowledge}"
+            else:
+                return f"Elicitation {result.action}"
+
+        proxy_server = FastMCP.as_proxy(ProxyClient(fastmcp_server))
+
+        # Test that elicitation works correctly through the proxy
+        async def elicitation_handler(
+            message: str,
+            response_type: type,
+            params: ElicitRequestParams,
+            ctx: RequestContext,
+        ):
+            # Verify the schema is correct - acknowledge should have default=False, not be nullable
+            schema = params.requestedSchema
+            assert schema["properties"]["acknowledge"]["type"] == "boolean"
+            assert schema["properties"]["acknowledge"]["default"] is False
+
+            return {"content": "Test content", "acknowledge": True}
+
+        async with Client(
+            proxy_server, elicitation_handler=elicitation_handler
+        ) as client:
+            result = await client.call_tool("elicit_with_defaults", {})
+            assert result.data == "Content: Test content, Acknowledge: True"
+
     async def test_client_factory_creates_fresh_sessions(self, fastmcp_server: FastMCP):
         """Test that the client factory pattern creates fresh sessions for each request."""
         from fastmcp.server.proxy import FastMCPProxy