diff --git a/pkg/octicons/octicons.go b/pkg/octicons/octicons.go
index 3c56f09c0..5954a8c22 100644
--- a/pkg/octicons/octicons.go
+++ b/pkg/octicons/octicons.go
@@ -73,12 +73,12 @@ func Icons(name string) []mcp.Icon {
 		{
 			Source:   DataURI(name, ThemeLight),
 			MIMEType: "image/png",
-			Theme:    string(ThemeLight),
+			Theme:    mcp.IconThemeLight,
 		},
 		{
 			Source:   DataURI(name, ThemeDark),
 			MIMEType: "image/png",
-			Theme:    string(ThemeDark),
+			Theme:    mcp.IconThemeDark,
 		},
 	}
 }
diff --git a/pkg/octicons/octicons_test.go b/pkg/octicons/octicons_test.go
index 27fc135ee..078eb744f 100644
--- a/pkg/octicons/octicons_test.go
+++ b/pkg/octicons/octicons_test.go
@@ -4,6 +4,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/modelcontextprotocol/go-sdk/mcp"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -87,13 +88,13 @@ func TestIcons(t *testing.T) {
 			assert.Equal(t, DataURI(tc.icon, ThemeLight), result[0].Source)
 			assert.Equal(t, "image/png", result[0].MIMEType)
 			assert.Empty(t, result[0].Sizes) // Sizes field omitted for backward compatibility
-			assert.Equal(t, "light", result[0].Theme)
+			assert.Equal(t, mcp.IconThemeLight, result[0].Theme)
 
 			// Verify second icon is dark theme
 			assert.Equal(t, DataURI(tc.icon, ThemeDark), result[1].Source)
 			assert.Equal(t, "image/png", result[1].MIMEType)
 			assert.Empty(t, result[1].Sizes) // Sizes field omitted for backward compatibility
-			assert.Equal(t, "dark", result[1].Theme)
+			assert.Equal(t, mcp.IconThemeDark, result[1].Theme)
 		})
 	}
 }