tag last tool w anthropic prompt cache

Author: dlants

node/providers/anthropic.ts

@@ -105,6 +105,28 @@ export class AnthropicProvider implements Provider {
       };
     });
 
+    const tools: Anthropic.Tool[] = ToolManager.TOOL_SPECS.map(
+      (t, idx): Anthropic.Tool => {
+        if (idx == ToolManager.TOOL_SPECS.length - 1) {
+          /** Assuming that the ordering when the prompt is sent to anthropic will be:
+           * system
+           * tools
+           *
+           * So marking the last tool with cache_control should use the first cache breakpoint to tag the end of this opening section.
+           */
+          return {
+            ...t,
+            input_schema: t.input_schema as Anthropic.Messages.Tool.InputSchema,
+            cache_control: { type: "ephemeral" },
+          };
+        }
+        return {
+          ...t,
+          input_schema: t.input_schema as Anthropic.Messages.Tool.InputSchema,
+        };
+      },
+    );
+
     try {
       this.request = this.client.messages
         .stream({
@@ -116,7 +138,7 @@ export class AnthropicProvider implements Provider {
             type: "auto",
             disable_parallel_tool_use: false,
           },
-          tools: ToolManager.TOOL_SPECS as Anthropic.Tool[],
+          tools,
         })
         .on("text", (text: string) => {
           buf.push(text);