Improve json output for tools that output json.

Author: ericdallo

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Added ability to cancel tool calls. Only the shell tool currently. #145
 - Bump mcp java sdk to 0.14.1.
+- Improve json output for tools that output json.
 
 ## 0.64.1
 

src/eca/features/tools.clj

@@ -2,6 +2,7 @@
   "This ns centralizes all available tools for LLMs including
    eca native tools and MCP servers."
   (:require
+   [cheshire.core :as json]
    [clojure.string :as string]
    [eca.features.tools.chat :as f.tools.chat]
    [eca.features.tools.custom :as f.tools.custom]
@@ -74,6 +75,27 @@
       (mapv #(assoc % :origin :native) (native-tools db config))
       (mapv #(assoc % :origin :mcp) (f.mcp/all-tools db))))))
 
+(defn ^:private pretty-format-any-json-output
+  [result]
+  (update result
+          :contents
+          (fn [contents]
+            (mapv (fn [content]
+                    (if (= :text (:type content))
+                      (let [text (string/trim (:text content))]
+                        (if (or (and (string/starts-with? text "{")
+                                     (string/ends-with? text "}"))
+                                (and (string/starts-with? text "[")
+                                     (string/ends-with? text "]")))
+                          (try
+                            (update content :text #(json/generate-string (json/parse-string %) {:pretty true}))
+                            (catch Exception e
+                              (println e)
+                              content))
+                          content))
+                      content))
+                  contents))))
+
 (defn call-tool! [^String name ^Map arguments chat-id tool-call-id behavior db* config messenger metrics
                   call-state-fn         ; thunk
                   state-transition-fn   ; params: event & event-data
@@ -82,25 +104,26 @@
   (let [arguments (update-keys arguments clojure.core/name)
         db @db*]
     (try
-      (let [result (if-let [native-tool-handler (get-in (native-definitions db config) [name :handler])]
-                     (native-tool-handler arguments {:db db
-                                                     :db* db*
-                                                     :config config
-                                                     :messenger messenger
-                                                     :behavior behavior
-                                                     :chat-id chat-id
-                                                     :tool-call-id tool-call-id
-                                                     :call-state-fn call-state-fn
-                                                     :state-transition-fn state-transition-fn})
-                     (f.mcp/call-tool! name arguments {:db db
-                                                       :db* db*
-                                                       :config config
-                                                       :messenger messenger
-                                                       :behavior behavior
-                                                       :chat-id chat-id
-                                                       :tool-call-id tool-call-id
-                                                       :call-state-fn call-state-fn
-                                                       :state-transition-fn state-transition-fn}))]
+      (let [result (-> (if-let [native-tool-handler (get-in (native-definitions db config) [name :handler])]
+                         (native-tool-handler arguments {:db db
+                                                         :db* db*
+                                                         :config config
+                                                         :messenger messenger
+                                                         :behavior behavior
+                                                         :chat-id chat-id
+                                                         :tool-call-id tool-call-id
+                                                         :call-state-fn call-state-fn
+                                                         :state-transition-fn state-transition-fn})
+                         (f.mcp/call-tool! name arguments {:db db
+                                                           :db* db*
+                                                           :config config
+                                                           :messenger messenger
+                                                           :behavior behavior
+                                                           :chat-id chat-id
+                                                           :tool-call-id tool-call-id
+                                                           :call-state-fn call-state-fn
+                                                           :state-transition-fn state-transition-fn}))
+                       (pretty-format-any-json-output))]
         (logger/debug logger-tag "Tool call result: " result)
         (metrics/count-up! "tool-called" {:name name :error (:error result)} metrics)
         result)

test/eca/features/tools_test.clj

@@ -4,6 +4,8 @@
    [eca.config :as config]
    [eca.features.tools :as f.tools]
    [eca.features.tools.filesystem :as f.tools.filesystem]
+   [eca.features.tools.mcp :as f.mcp]
+   [eca.shared :refer [multi-str]]
    [eca.test-helper :as h]
    [matcher-combinators.matchers :as m]
    [matcher-combinators.test :refer [match?]]))
@@ -188,3 +190,27 @@
         ;; Test safe commands that should NOT be denied
         (is (= :ask (f.tools/approval all-tools "eca_shell_command" {"command" "ls -la"} {} config "plan")))
         (is (= :ask (f.tools/approval all-tools "eca_shell_command" {"command" "git status"} {} config "plan")))))))
+
+(deftest call-tool!-test
+  (testing "We adapt output if json"
+    (is (match?
+         {:contents [{:type :text
+                      :text (multi-str "{"
+                                       "  \"foo\" : \"123\","
+                                       "  \"bar\" : 234"
+                                       "}")}]
+          :error false}
+         (with-redefs [f.mcp/call-tool! (constantly {:contents [{:type :text
+                                                                 :text "{\"foo\": \"123\", \"bar\": 234}"}]
+                                                     :error false})]
+           (f.tools/call-tool! "my-json-tool"
+                               {}
+                               "chat-123"
+                               "tool-234"
+                               "agent"
+                               (h/db*)
+                               (h/config)
+                               (h/messenger)
+                               (h/metrics)
+                               identity
+                               identity))))))