fix: properly type tool error content in getAITools (#781)

* fix: properly type tool error content in getAITools

* fix: cast result.content to fix TS18046 error

- Cast result.content to Array<{ type: string; text?: string }> | undefined
- Add additional null check for textContent.text
- Add changeset for patch release

Author: HueCodes

.changeset/fix-mcp-error-type.md

@@ -0,0 +1,5 @@
+---
+"agents": patch
+---
+
+fix: properly type tool error content in getAITools

packages/agents/src/mcp/client.ts

@@ -941,8 +941,15 @@ export class MCPClientManager {
                 serverId: tool.serverId
               });
               if (result.isError) {
-                // @ts-expect-error TODO we should fix this
-                throw new Error(result.content[0].text);
+                const content = result.content as
+                  | Array<{ type: string; text?: string }>
+                  | undefined;
+                const textContent = content?.[0];
+                const message =
+                  textContent?.type === "text" && textContent.text
+                    ? textContent.text
+                    : "Tool call failed";
+                throw new Error(message);
               }
               return result;
             },