fix: forward original tool name to remote MCP servers

When tool-name-prefix is enabled, the gateway prefixes tool names
(e.g., 'new_page' becomes 'server__new_page'). However, when forwarding
the call to the remote server, the prefixed name was being sent instead
of the original name.

The remote server doesn't know about gateway prefixes and fails with
'tool not found'.

This fix:
1. Adds originalToolName parameter to mcpServerToolHandler
2. Passes the original tool.Name when creating handlers
3. Uses originalToolName when calling the remote server

Tested with custom MCP servers using explicit prefix configuration.

Author: null-runner

pkg/gateway/capabilitites.go

@@ -159,7 +159,7 @@ func (g *Gateway) listCapabilities(ctx context.Context, serverNames []string, cl
 						capabilities.Tools = append(capabilities.Tools, ToolRegistration{
 							ServerName: serverConfig.Name,
 							Tool:       &prefixedTool,
-							Handler:    g.mcpServerToolHandler(serverConfig.Name, g.mcpServer, tool.Annotations),
+							Handler:    g.mcpServerToolHandler(serverConfig.Name, g.mcpServer, tool.Annotations, tool.Name),
 						})
 					}
 				}

pkg/gateway/handlers.go

@@ -57,7 +57,7 @@ func (g *Gateway) mcpToolHandler(tool catalog.Tool) mcp.ToolHandler {
 	}
 }
 
-func (g *Gateway) mcpServerToolHandler(serverName string, server *mcp.Server, annotations *mcp.ToolAnnotations) mcp.ToolHandler {
+func (g *Gateway) mcpServerToolHandler(serverName string, server *mcp.Server, annotations *mcp.ToolAnnotations, originalToolName string) mcp.ToolHandler {
 	return func(ctx context.Context, req *mcp.CallToolRequest) (*mcp.CallToolResult, error) {
 		// Look up server configuration
 		serverConfig, _, ok := g.configuration.Find(serverName)
@@ -128,7 +128,7 @@ func (g *Gateway) mcpServerToolHandler(serverName string, server *mcp.Server, an
 		}
 		params := &mcp.CallToolParams{
 			Meta:      req.Params.Meta,
-			Name:      req.Params.Name,
+			Name:      originalToolName,
 			Arguments: args,
 		}