From 4364a771d443ba7a18e5144e073bbeb08eca697f Mon Sep 17 00:00:00 2001
From: Zamil Majdy <zamil.majdy@agpt.co>
Date: Tue, 10 Feb 2026 15:42:51 +0400
Subject: [PATCH] fix(mcp): Validate required tool args and fix title fallback
 for existing blocks

Backend: Add required-field validation in MCPToolBlock.run() before
calling the MCP server. The executor-level validation is bypassed for
MCP blocks because get_input_defaults() flattens tool_arguments,
stripping tool_input_schema from the validation context.

Frontend: NodeHeader now derives the MCP server label from the server
URL hostname when server_name is missing (pruned by pruneEmptyValues).
This fixes the title for existing blocks that don't have customized_name
in metadata.
---
 .../backend/backend/blocks/mcp/block.py          | 14 ++++++++++++++
 .../nodes/CustomNode/components/NodeHeader.tsx   | 16 +++++++++++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/autogpt_platform/backend/backend/blocks/mcp/block.py b/autogpt_platform/backend/backend/blocks/mcp/block.py
index ebb7aacc6b..92a57e7477 100644
--- a/autogpt_platform/backend/backend/blocks/mcp/block.py
+++ b/autogpt_platform/backend/backend/blocks/mcp/block.py
@@ -260,6 +260,20 @@ class MCPToolBlock(Block):
             yield "error", "No tool selected. Please select a tool from the dropdown."
             return
 
+        # Validate required tool arguments before calling the server.
+        # The executor-level validation is bypassed for MCP blocks because
+        # get_input_defaults() flattens tool_arguments, stripping tool_input_schema
+        # from the validation context.
+        required = set(input_data.tool_input_schema.get("required", []))
+        if required:
+            missing = required - set(input_data.tool_arguments.keys())
+            if missing:
+                yield "error", (
+                    f"Missing required argument(s): {', '.join(sorted(missing))}. "
+                    f"Please fill in all required fields marked with * in the block form."
+                )
+                return
+
         # If no credentials were injected by the executor (e.g. legacy nodes
         # that don't have the credentials field set), try to auto-lookup
         # the stored MCP credential for this server URL.
diff --git a/autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/nodes/CustomNode/components/NodeHeader.tsx b/autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/nodes/CustomNode/components/NodeHeader.tsx
index 817fe39bfe..a37cda2159 100644
--- a/autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/nodes/CustomNode/components/NodeHeader.tsx
+++ b/autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/nodes/CustomNode/components/NodeHeader.tsx
@@ -25,10 +25,24 @@ export const NodeHeader = ({ data, nodeId }: Props) => {
     data.block_id === SpecialBlockID.MCP_TOOL &&
     !!data.hardcodedValues?.selected_tool;
 
+  // Derive MCP server label: prefer server_name, fall back to URL hostname.
+  let mcpServerLabel = "MCP";
+  if (isMCPWithTool) {
+    mcpServerLabel =
+      data.hardcodedValues.server_name ||
+      (() => {
+        try {
+          return new URL(data.hardcodedValues.server_url).hostname;
+        } catch {
+          return "MCP";
+        }
+      })();
+  }
+
   const title =
     (data.metadata?.customized_name as string) ||
     (isMCPWithTool
-      ? `${data.hardcodedValues.server_name || "MCP"}: ${beautifyString(data.hardcodedValues.selected_tool)}`
+      ? `${mcpServerLabel}: ${beautifyString(data.hardcodedValues.selected_tool)}`
       : null) ||
     data.hardcodedValues?.agent_name ||
     data.title;