feat: support standalone toolset metadata in inventory builder

- Added `toolsetMetadata` field to Builder for registering standalone toolset metadata
- Added `SetToolsetMetadata()` method to Builder for setting standalone metadata
- Updated `processToolsets()` to include standalone metadata in default toolsets
- Updated `NewInventory()` to register remote-only toolset metadata
- Updated test expectations to include `copilot` in defaults

This change enables toolset metadata with `Default: true` to control whether
tools in that toolset are included by default, even if no tools in the OSS
repo use that toolset. The remote server can now register tools in the
`copilot` toolset and they will automatically be included in defaults.

Co-authored-by: SamMorrowDrums <4811358+SamMorrowDrums@users.noreply.github.com>

Author: Copilot

internal/ghmcp/server.go

@@ -215,7 +215,7 @@ func NewMCPServer(cfg MCPServerConfig) (*mcp.Server, error) {
 		cfg.Translator,
 		github.FeatureFlags{
 			LockdownMode: cfg.LockdownMode,
-			InsiderMode: cfg.InsiderMode,
+			InsiderMode:  cfg.InsiderMode,
 		},
 		cfg.ContentWindowSize,
 		featureChecker,
@@ -235,7 +235,7 @@ func NewMCPServer(cfg MCPServerConfig) (*mcp.Server, error) {
 		WithToolsets(enabledToolsets).
 		WithTools(cfg.EnabledTools).
 		WithFeatureChecker(featureChecker)
-  
+
 	// Apply token scope filtering if scopes are known (for PAT filtering)
 	if cfg.TokenScopes != nil {
 		inventoryBuilder = inventoryBuilder.WithFilter(github.CreateToolScopeFilter(cfg.TokenScopes))

pkg/github/inventory.go

@@ -14,5 +14,6 @@ func NewInventory(t translations.TranslationHelperFunc) *inventory.Builder {
 	return inventory.NewBuilder().
 		SetTools(AllTools(t)).
 		SetResources(AllResources(t)).
-		SetPrompts(AllPrompts(t))
+		SetPrompts(AllPrompts(t)).
+		SetToolsetMetadata(RemoteOnlyToolsets())
 }

pkg/github/tools_test.go

@@ -23,6 +23,7 @@ func TestAddDefaultToolset(t *testing.T) {
 			input: []string{"default"},
 			expected: []string{
 				"context",
+				"copilot",
 				"repos",
 				"issues",
 				"pull_requests",
@@ -36,6 +37,7 @@ func TestAddDefaultToolset(t *testing.T) {
 				"actions",
 				"gists",
 				"context",
+				"copilot",
 				"repos",
 				"issues",
 				"pull_requests",
@@ -47,6 +49,7 @@ func TestAddDefaultToolset(t *testing.T) {
 			input: []string{"default", "context", "repos"},
 			expected: []string{
 				"context",
+				"copilot",
 				"repos",
 				"issues",
 				"pull_requests",

pkg/inventory/builder.go

@@ -32,6 +32,7 @@ type Builder struct {
 	resourceTemplates []ServerResourceTemplate
 	prompts           []ServerPrompt
 	deprecatedAliases map[string]string
+	toolsetMetadata   []ToolsetMetadata // standalone toolset metadata
 
 	// Configuration options (processed at Build time)
 	readOnly        bool
@@ -68,6 +69,16 @@ func (b *Builder) SetPrompts(prompts []ServerPrompt) *Builder {
 	return b
 }
 
+// SetToolsetMetadata sets standalone toolset metadata for the inventory.
+// This is used for toolsets that may not have tools registered in this build
+// but should still be recognized (e.g., remote-only toolsets).
+// Toolsets with Default: true will be included in default toolsets even if
+// no tools use them. Returns self for chaining.
+func (b *Builder) SetToolsetMetadata(metadata []ToolsetMetadata) *Builder {
+	b.toolsetMetadata = metadata
+	return b
+}
+
 // WithDeprecatedAliases adds deprecated tool name aliases that map to canonical names.
 // Returns self for chaining.
 func (b *Builder) WithDeprecatedAliases(aliases map[string]string) *Builder {
@@ -248,6 +259,17 @@ func (b *Builder) processToolsets() (map[ToolsetID]bool, []string, []ToolsetID,
 			descriptions[p.Toolset.ID] = p.Toolset.Description
 		}
 	}
+	// Process standalone toolset metadata
+	for i := range b.toolsetMetadata {
+		m := &b.toolsetMetadata[i]
+		validIDs[m.ID] = true
+		if m.Default {
+			defaultIDs[m.ID] = true
+		}
+		if m.Description != "" {
+			descriptions[m.ID] = m.Description
+		}
+	}
 
 	// Build sorted slices from the collected maps
 	allToolsetIDs := make([]ToolsetID, 0, len(validIDs))