diff --git a/agent/README.md b/agent/README.md
index 4a77017..57b1c74 100644
--- a/agent/README.md
+++ b/agent/README.md
@@ -1,3 +1,22 @@
 ## Refining the agent output
 
-TODO: Table and document experiments
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+Experiments modifying pipeline
+
+| Model            | % Correct | % Change |
+|------------------|----------:|---------:|
+| BASELINE         | 33        | 0        |
+| Improv Prompt    | 39.96     | 0.21     |
+| Add Examples     | 44.67     | 0.35     |
+| Date             | 45.51     | 0.38     |
+| Chain of Thought | 43.38     | 0.31     |
+| Self-Critique    | 44.36     | 0.34     |
+
+Experiments with different model types:
+| Model                         | % Correct | % Change |
+|-------------------------------|----------:|---------:|
+| gpt-5-mini                    | 33        | 0        |
+| gpt-5.4-mini                  | 32.4      | -0.02    |
+| llama3.1:8b-instruct-q4_K_M   | ?         | ?        |
+| qwen3.5:9b                    | 0         | -100     |
+
+%age correct URLS
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diff --git a/supporting/checker/checker.py b/supporting/checker/checker.py
new file mode 100644
index 0000000..6749066
--- /dev/null
+++ b/supporting/checker/checker.py
@@ -0,0 +1,104 @@
+import json
+import argparse
+from urllib.parse import urlparse
+from selenium import webdriver
+from selenium.webdriver.chrome.options import Options
+from selenium.common.exceptions import WebDriverException, TimeoutException
+
+def init_driver():
+    options = Options()
+    options.headless = True
+    options.add_argument("--disable-gpu")
+    options.add_argument("--no-sandbox")
+    options.add_argument("--disable-blink-features=AutomationControlled")
+    options.add_argument("--window-size=1920,1080")
+    driver = webdriver.Chrome(options=options)
+    driver.set_page_load_timeout(15)
+    return driver
+
+def is_root_url(url):
+    """Return True if URL is a root domain with no path."""
+    parsed = urlparse(url)
+    return parsed.path in ("", "/")
+
+def is_404_page(driver):
+    """Check for 404 indicators in title or body text."""
+    title = driver.title.lower()
+    body_text = driver.find_element("tag name", "body").text.lower()
+    if "404" in title or "not found" in title:
+        return True
+    if "404" in body_text or "not found" in body_text:
+        return True
+    return False
+
+def check_url_selenium(driver, url):
+    """
+    Check if a URL is valid:
+    - Loads without error
+    - Not a 404 page
+    - Not redirected to a root domain
+    """
+    try:
+        driver.get(url)
+        # 1️⃣ Check if page is 404
+        if is_404_page(driver):
+            print(f"Page returned 404: {url}")
+            return False
+        # 2️⃣ Check if current URL after redirects is a root URL
+        final_url = driver.current_url
+        if is_root_url(final_url):
+            print(f"Redirected to root URL (invalid): {final_url}")
+            return False
+        return True
+    except (WebDriverException, TimeoutException) as e:
+        print(f"Error accessing URL {url}: {e}")
+        return False
+
+def process_event(event, driver, invalid_urls):
+    url = event.get("Url")
+    if url:
+        is_valid = check_url_selenium(driver, url)
+        event["url_valid"] = is_valid
+        if not is_valid:
+            invalid_urls.append(url)
+        return is_valid
+    return False
+
+def process_jsonl_file(file_path):
+    total_urls = 0
+    valid_urls = 0
+    invalid_urls = []
+
+    driver = init_driver()
+
+    with open(file_path, "r", encoding="utf-8") as f:
+        for line in f:
+            line_data = json.loads(line)
+
+            if line_data.get("status") != "success":
+                continue
+
+            events = line_data.get("events", [])
+            for event in events:
+                total_urls += 1
+                if process_event(event, driver, invalid_urls):
+                    valid_urls += 1
+
+    driver.quit()
+
+    # Summary
+    print("\n=== URL Validation Summary ===")
+    print(f"Total URLs processed: {total_urls}")
+    print(f"Valid URLs (loaded successfully): {valid_urls}")
+    print(f"Invalid URLs: {len(invalid_urls)}")
+    if invalid_urls:
+        print("\nList of invalid URLs:")
+        for url in invalid_urls:
+            print(url)
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Validate URLs in JSONL file events using Selenium")
+    parser.add_argument("file_path", type=str, help="Path to the JSONL file")
+    args = parser.parse_args()
+
+    process_jsonl_file(args.file_path)
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