diff --git a/x-pack/plugins/inference/scripts/util/kibana_client.ts b/x-pack/plugins/inference/scripts/util/kibana_client.ts
index f8e96cfcf4ae3..ca26ef76b2c72 100644
--- a/x-pack/plugins/inference/scripts/util/kibana_client.ts
+++ b/x-pack/plugins/inference/scripts/util/kibana_client.ts
@@ -179,6 +179,7 @@ export class KibanaClient {
       system,
       toolChoice,
       tools,
+      functionCalling,
     }) => {
       const body: ChatCompleteRequestBody = {
         connectorId: chatCompleteConnectorId,
@@ -186,6 +187,7 @@ export class KibanaClient {
         messages,
         toolChoice,
         tools,
+        functionCalling,
       };
 
       return stream(
diff --git a/x-pack/plugins/inference/server/chat_complete/simulated_function_calling/get_system_instructions.ts b/x-pack/plugins/inference/server/chat_complete/simulated_function_calling/get_system_instructions.ts
index 872e842e03f86..848b8d1f44f07 100644
--- a/x-pack/plugins/inference/server/chat_complete/simulated_function_calling/get_system_instructions.ts
+++ b/x-pack/plugins/inference/server/chat_complete/simulated_function_calling/get_system_instructions.ts
@@ -29,9 +29,18 @@ export function getSystemMessageInstructions({
 
     It is EXTREMELY important that you generate valid JSON between the \`\`\`json and \`\`\` delimiters.
 
-    You may call them like this.
+    IMPORTANT: make sure you start and end a tool call with the ${TOOL_USE_START} and ${TOOL_USE_END} markers, it MUST
+    be included in the tool call.
 
-    Given the following tool:
+    You may call tools like this:
+
+    ${TOOL_USE_START}
+    \`\`\`json
+    ${JSON.stringify({ name: '[name of the tool]', input: { myProperty: 'myValue' } })}
+    \`\`\`\
+    ${TOOL_USE_END}
+
+    For example, given the following tool:
 
     ${JSON.stringify({
       name: 'my_tool',
@@ -54,13 +63,15 @@ export function getSystemMessageInstructions({
     \`\`\`\
     ${TOOL_USE_END}
 
-    Given the following tool:
+    Another example: given the following tool:
+
     ${JSON.stringify({
       name: 'my_tool_without_parameters',
       description: 'A tool to call without parameters',
     })}
 
     Use it the following way:
+
     ${TOOL_USE_START}
     \`\`\`json
     ${JSON.stringify({ name: 'my_tool_without_parameters', input: {} })}
diff --git a/x-pack/plugins/inference/server/chat_complete/simulated_function_calling/parse_inline_function_calls.ts b/x-pack/plugins/inference/server/chat_complete/simulated_function_calling/parse_inline_function_calls.ts
index 2fa9dd899e986..3436d7a7edac5 100644
--- a/x-pack/plugins/inference/server/chat_complete/simulated_function_calling/parse_inline_function_calls.ts
+++ b/x-pack/plugins/inference/server/chat_complete/simulated_function_calling/parse_inline_function_calls.ts
@@ -45,7 +45,7 @@ export function parseInlineFunctionCalls({ logger }: { logger: Logger }) {
           logger.debug('Parsing function call:\n' + buffer);
 
           const match = buffer.match(
-            /<\|tool_use_start\|>\s*```json\n?(.*?)(\n```\s*).*<\|tool_use_end\|>/s
+            /<\|tool_use_start\|>\s*```json\n?(.*?)(\n?```\s*).*<\|tool_use_end\|>/s
           );
 
           const functionCallBody = match?.[1];
diff --git a/x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/adapters/simulate_function_calling/get_system_message_instructions.ts b/x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/adapters/simulate_function_calling/get_system_message_instructions.ts
index a409a80716320..c80ac022ca6c0 100644
--- a/x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/adapters/simulate_function_calling/get_system_message_instructions.ts
+++ b/x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/adapters/simulate_function_calling/get_system_message_instructions.ts
@@ -29,10 +29,19 @@ export function getSystemMessageInstructions({
     If a tool does not have properties, leave them out.
 
     It is EXTREMELY important that you generate valid JSON between the \`\`\`json and \`\`\` delimiters.
-    
-    You may call them like this.
 
-    Given the following tool:
+    IMPORTANT: make sure you start and end a tool call with the ${TOOL_USE_START} and ${TOOL_USE_END} markers, it MUST
+    be included in the tool call.
+
+    You may call tools like this:
+
+    ${TOOL_USE_START}
+    \`\`\`json
+    ${JSON.stringify({ name: '[name of the tool]', input: { myProperty: 'myValue' } })}
+    \`\`\`\
+    ${TOOL_USE_END}
+
+    For example, given the following tool:
 
     ${JSON.stringify({
       name: 'my_tool',
@@ -55,13 +64,15 @@ export function getSystemMessageInstructions({
     \`\`\`\
     ${TOOL_USE_END}
 
-    Given the following tool:
+    Another example: given the following tool:
+
     ${JSON.stringify({
       name: 'my_tool_without_parameters',
       description: 'A tool to call without parameters',
     })}
 
-    Use it the following way: 
+    Use it the following way:
+
     ${TOOL_USE_START}
     \`\`\`json
     ${JSON.stringify({ name: 'my_tool_without_parameters', input: {} })}
@@ -77,7 +88,7 @@ export function getSystemMessageInstructions({
         ...(fn.parameters ? { parameters: fn.parameters } : {}),
       }))
     )}
-    
+
     `;
   }
 
diff --git a/x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/adapters/simulate_function_calling/parse_inline_function_calls.ts b/x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/adapters/simulate_function_calling/parse_inline_function_calls.ts
index 82a613ef0b4f8..4ae3c5bf746e3 100644
--- a/x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/adapters/simulate_function_calling/parse_inline_function_calls.ts
+++ b/x-pack/plugins/observability_solution/observability_ai_assistant/server/service/client/adapters/simulate_function_calling/parse_inline_function_calls.ts
@@ -44,7 +44,7 @@ export function parseInlineFunctionCalls({ logger }: { logger: Logger }) {
         logger.debug('Parsing function call:\n' + buffer);
 
         const match = buffer.match(
-          /<\|tool_use_start\|>\s*```json\n?(.*?)(\n```\s*).*<\|tool_use_end\|>/s
+          /<\|tool_use_start\|>\s*```json\n?(.*?)(\n?```\s*).*<\|tool_use_end\|>/s
         );
 
         const functionCallBody = match?.[1];
diff --git a/x-pack/plugins/observability_solution/observability_ai_assistant_app/scripts/evaluation/kibana_client.ts b/x-pack/plugins/observability_solution/observability_ai_assistant_app/scripts/evaluation/kibana_client.ts
index 8246a9ceae71f..ddfa4c98765f7 100644
--- a/x-pack/plugins/observability_solution/observability_ai_assistant_app/scripts/evaluation/kibana_client.ts
+++ b/x-pack/plugins/observability_solution/observability_ai_assistant_app/scripts/evaluation/kibana_client.ts
@@ -110,7 +110,7 @@ export class KibanaClient {
     const url = format({
       ...parsed,
       pathname: `/${[
-        baseUrl,
+        ...(baseUrl ? [baseUrl] : []),
         ...(props.ignoreSpaceId || !this.spaceId ? [] : ['s', this.spaceId]),
         props.pathname.startsWith('/') ? props.pathname.substring(1) : props.pathname,
       ].join('/')}`,