diff --git a/cmd/olliesrv/internal/agent/prompt_resolver.go b/cmd/olliesrv/internal/agent/prompt_resolver.go
index 97bfe54..29c06ba 100644
--- a/cmd/olliesrv/internal/agent/prompt_resolver.go
+++ b/cmd/olliesrv/internal/agent/prompt_resolver.go
@@ -49,6 +49,7 @@ func resolvePrompt(p Prompt, cwd string, env []string) (string, error) {
 }
 
 // envLookup returns a lookup function that checks env slice first, then os env.
+// Provides XDG spec defaults when variables are unset.
 func envLookup(env []string) func(string) string {
 	m := make(map[string]string, len(env))
 	for _, e := range env {
@@ -56,11 +57,24 @@ func envLookup(env []string) func(string) string {
 			m[k] = v
 		}
 	}
+	home, _ := os.UserHomeDir()
 	return func(key string) string {
 		if v, ok := m[key]; ok {
 			return v
 		}
-		return os.Getenv(key)
+		if v := os.Getenv(key); v != "" {
+			return v
+		}
+		// XDG spec defaults
+		switch key {
+		case "XDG_CONFIG_HOME":
+			return home + "/.config"
+		case "XDG_DATA_HOME":
+			return home + "/.local/share"
+		case "XDG_CACHE_HOME":
+			return home + "/.cache"
+		}
+		return ""
 	}
 }
 
diff --git a/cmd/olliesrv/internal/agent/runtime.go b/cmd/olliesrv/internal/agent/runtime.go
index b38c5a0..3641a33 100644
--- a/cmd/olliesrv/internal/agent/runtime.go
+++ b/cmd/olliesrv/internal/agent/runtime.go
@@ -100,12 +100,18 @@ func renderTools(infos []toolsrv.ToolInfo) string {
 		if ti.Description == "" {
 			continue
 		}
-		sb.WriteString("## ")
-		sb.WriteString(ti.Name)
-		sb.WriteString("\n\n")
 		if ti.Prompt != "" {
+			// If prompt already starts with a markdown header, skip the generated one.
+			if !strings.HasPrefix(ti.Prompt, "#") {
+				sb.WriteString("## ")
+				sb.WriteString(ti.Name)
+				sb.WriteString("\n\n")
+			}
 			sb.WriteString(ti.Prompt)
 		} else {
+			sb.WriteString("## ")
+			sb.WriteString(ti.Name)
+			sb.WriteString("\n\n")
 			sb.WriteString(ti.Description)
 		}
 		sb.WriteString("\n\n")