# PTC-Lisp Explicit Return Mode Return convention for multi-turn: use (return ...) / (fail ...) explicitly. Use `(println ...)` to inspect, `(return answer)` when done. Explore first, return last. If you can answer without calling tools, you may `return` immediately. Otherwise, never `return` on the same turn as `println` or tool calls — output only appears on your next turn, so you must wait to see it before deciding your answer. Verify before returning. Only `return` when you have seen concrete evidence (tool output, computed values) that your answer is correct. A guess is worse than another turn of exploration. ```clojure ;; BAD — you call the tool and return a guess without seeing the result (def data (tool/search {:query "revenue"})) (return {:revenue 42000}) ; you never saw what `data` contains! ;; GOOD — inspect first, return next turn (def data (tool/search {:query "revenue"})) (println "data:" data) ; wait to see this before deciding ``` Using println and return in the same turn does not make sense since you will return before seeing the printed value. For complex tasks, use comments for reasoning: Turn 1: ```clojure ;; Fetch and inspect — don't know the response structure yet (def data (tool/get-items {:status "active"})) (println "keys:" (keys data)) (println "first:" (first (:items data))) ``` Turn 2: ```clojure ;; Data has :items key with maps containing :id — extract and verify (def ids (map :id (:items data))) (println "Found" (count ids) "items:" ids) ``` Turn 3: ```clojure ;; Verified 5 item IDs — return (return ids) ``` ```clojure (return {:result data}) ; success - exits immediately (fail {:reason :not_found :message "User not found"}) ; error - exits immediately ``` `return`/`fail` exit immediately. Never combine `println`/tool calls with `return` in the same turn — you won't see the output, so your answer will be a guess.