From 76f6ce5340ccafe60182ff072da65e4078c25f8f Mon Sep 17 00:00:00 2001
From: KoheiYamashita <yamashita@0235.co.jp>
Date: Mon, 23 Feb 2026 01:57:05 +0900
Subject: [PATCH] feat: add MCP resource reading and fix HTTP transport hang

- Add ReadResource method to MCP Manager for reading server resources
- Add mcp_read_resource action to MCPBridgeTool so LLM can read MCP
  resources like data type catalogs
- Set DisableStandaloneSSE=true on StreamableClientTransport to prevent
  connection hang when server/proxy doesn't support standalone SSE GET

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 pkg/mcp/manager.go | 41 +++++++++++++++++++++++++++++++++++++++--
 pkg/tools/mcp.go   | 29 +++++++++++++++++++++++++++--
 2 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/pkg/mcp/manager.go b/pkg/mcp/manager.go
index 9e9915c20..937398506 100644
--- a/pkg/mcp/manager.go
+++ b/pkg/mcp/manager.go
@@ -156,6 +156,42 @@ func (m *Manager) CallTool(ctx context.Context, serverName, toolName string, arg
 	return text, nil
 }
 
+// ReadResource reads a resource from an MCP server by URI.
+func (m *Manager) ReadResource(ctx context.Context, serverName, uri string) (string, error) {
+	inst, err := m.ensureRunning(ctx, serverName)
+	if err != nil {
+		return "", err
+	}
+
+	inst.mu.Lock()
+	defer inst.mu.Unlock()
+
+	inst.lastUsed = time.Now()
+
+	result, err := inst.session.ReadResource(ctx, &sdkmcp.ReadResourceParams{
+		URI: uri,
+	})
+	if err != nil {
+		m.handleSessionError(serverName, inst, err)
+		return "", fmt.Errorf("resources/read %s: %w", uri, err)
+	}
+
+	var parts []string
+	for _, content := range result.Contents {
+		if content.Text != "" {
+			parts = append(parts, content.Text)
+		} else if len(content.Blob) > 0 {
+			parts = append(parts, fmt.Sprintf("[blob: %s, %d bytes]", content.MIMEType, len(content.Blob)))
+		}
+	}
+
+	if len(parts) == 0 {
+		return "(no content)", nil
+	}
+
+	return strings.Join(parts, "\n"), nil
+}
+
 // BuildSummary generates XML for the system prompt using config only (no process start).
 func (m *Manager) BuildSummary() string {
 	m.mu.RLock()
@@ -280,8 +316,9 @@ func (m *Manager) ensureRunning(ctx context.Context, serverName string) (*Server
 			}
 		}
 		transport = &sdkmcp.StreamableClientTransport{
-			Endpoint:   cfg.URL,
-			HTTPClient: httpClient,
+			Endpoint:             cfg.URL,
+			HTTPClient:           httpClient,
+			DisableStandaloneSSE: true,
 		}
 		inst.isHTTP = true
 
diff --git a/pkg/tools/mcp.go b/pkg/tools/mcp.go
index f3c5550f8..079eb73d2 100644
--- a/pkg/tools/mcp.go
+++ b/pkg/tools/mcp.go
@@ -24,7 +24,7 @@ func (t *MCPBridgeTool) Name() string {
 }
 
 func (t *MCPBridgeTool) Description() string {
-	return "Interact with MCP (Model Context Protocol) servers. Actions: mcp_list (list available servers), mcp_tools (get server's tool list), mcp_call (call a server tool)"
+	return "Interact with MCP (Model Context Protocol) servers. Actions: mcp_list (list available servers), mcp_tools (get server's tool list), mcp_call (call a server tool), mcp_read_resource (read a resource by URI)"
 }
 
 func (t *MCPBridgeTool) Parameters() map[string]interface{} {
@@ -34,7 +34,7 @@ func (t *MCPBridgeTool) Parameters() map[string]interface{} {
 			"action": map[string]interface{}{
 				"type":        "string",
 				"description": "The MCP action to perform",
-				"enum":        []string{"mcp_list", "mcp_tools", "mcp_call"},
+				"enum":        []string{"mcp_list", "mcp_tools", "mcp_call", "mcp_read_resource"},
 			},
 			"server": map[string]interface{}{
 				"type":        "string",
@@ -48,6 +48,10 @@ func (t *MCPBridgeTool) Parameters() map[string]interface{} {
 				"type":        "object",
 				"description": "Arguments to pass to the tool (for mcp_call)",
 			},
+			"uri": map[string]interface{}{
+				"type":        "string",
+				"description": "Resource URI to read (required for mcp_read_resource)",
+			},
 		},
 		"required": []string{"action"},
 	}
@@ -66,6 +70,8 @@ func (t *MCPBridgeTool) Execute(ctx context.Context, args map[string]interface{}
 		return t.getTools(ctx, args)
 	case "mcp_call":
 		return t.callTool(ctx, args)
+	case "mcp_read_resource":
+		return t.readResource(ctx, args)
 	default:
 		return ErrorResult(fmt.Sprintf("unknown action: %s", action))
 	}
@@ -142,3 +148,22 @@ func (t *MCPBridgeTool) callTool(ctx context.Context, args map[string]interface{
 
 	return SilentResult(result)
 }
+
+func (t *MCPBridgeTool) readResource(ctx context.Context, args map[string]interface{}) *ToolResult {
+	server, ok := args["server"].(string)
+	if !ok || server == "" {
+		return ErrorResult("server is required for mcp_read_resource")
+	}
+
+	uri, ok := args["uri"].(string)
+	if !ok || uri == "" {
+		return ErrorResult("uri is required for mcp_read_resource")
+	}
+
+	result, err := t.manager.ReadResource(ctx, server, uri)
+	if err != nil {
+		return ErrorResult(fmt.Sprintf("mcp_read_resource %s/%s failed: %v", server, uri, err))
+	}
+
+	return SilentResult(result)
+}