diff --git a/public/scripts/tool-calling.js b/public/scripts/tool-calling.js
index 26ae26091..677abc16e 100644
--- a/public/scripts/tool-calling.js
+++ b/public/scripts/tool-calling.js
@@ -88,6 +88,15 @@ function tryParse(str) {
     }
 }
 
+/**
+ * Stringifies an object if it is not already a string.
+ * @param {any} obj The object to stringify
+ * @returns {string} A JSON string representation of the object.
+ */
+function stringify(obj) {
+    return typeof obj === 'string' ? obj : JSON.stringify(obj);
+}
+
 /**
  * A class that represents a tool definition.
  */
@@ -571,7 +580,7 @@ export class ToolManager {
                 id,
                 displayName,
                 name,
-                parameters,
+                parameters: stringify(parameters),
                 result: toolResult,
             };
             result.invocations.push(invocation);
diff --git a/src/prompt-converters.js b/src/prompt-converters.js
index 0d1412301..19afabbaf 100644
--- a/src/prompt-converters.js
+++ b/src/prompt-converters.js
@@ -131,13 +131,14 @@ function convertClaudeMessages(messages, prefillString, useSysPrompt, humanMsgFi
     }
 
     // Now replace all further messages that have the role 'system' with the role 'user'. (or all if we're not using one)
+    const parse = (str) => typeof str === 'string' ? JSON.parse(str) : str;
     messages.forEach((message) => {
         if (message.role === 'assistant' && message.tool_calls) {
             message.content = message.tool_calls.map((tc) => ({
                 type: 'tool_use',
                 id: tc.id,
                 name: tc.function.name,
-                input: tc.function.arguments,
+                input: parse(tc.function.arguments),
             }));
         }