diff --git a/README.md b/README.md
index 3f80ac6..994f747 100644
--- a/README.md
+++ b/README.md
@@ -197,7 +197,7 @@ Optional email:
     ]
 - SCHEDULED_SEND_INTERVAL: Seconds between checks for scheduled emails (default: 10).
 
-HTML and signature:
+HTML, signature, and LLM identity:
 
 - Emails (send_email, reply_to_message, forward_message, schedule_send) default to HTML (html=true) unless explicitly set to false.
 - EMAIL_HTML_SIGNATURE: Optional HTML signature appended to HTML emails.
@@ -210,6 +210,45 @@ HTML and signature:
           -e EMAIL_HTML_SIGNATURE='/etc/mcp-email/signature.html'
     If the value is an existing file path, its contents are used as the signature.
 
+- Signature template variables:
+  - The signature can include placeholders:
+    - {{NAME}}
+    - {{TITLE}}
+    - {{PHONE}}
+    - {{ADDRESS}}
+    - {{EMAIL}}
+  - These are filled in using:
+    - Per-call LLM identity (signature_vars), or
+    - Fallback environment variables:
+        LLM_NAME, LLM_TITLE, LLM_PHONE, LLM_ADDRESS, LLM_EMAIL
+  - Example env-based defaults:
+      -e LLM_NAME='Adam P. Strömbergsson-DeNora'
+      -e LLM_TITLE='Barrister & Solicitor'
+      -e LLM_PHONE='1 613 699 2127'
+      -e LLM_ADDRESS='7th floor - 1 Rideau St. Ottawa, ON. K1N 8S7'
+      -e LLM_EMAIL='adam@apstrom.ca'
+
+- LLM identity via MCP (signature_vars):
+  - When sending, replying, forwarding, or scheduling an email, the LLM should include its identity so the signature is populated correctly.
+  - Example (send_email):
+      {
+        "name": "send_email",
+        "arguments": {
+          "to": ["client@example.com"],
+          "subject": "Your subject",
+          "body": "<p>Hello,</p><p>...</p>",
+          "html": true,
+          "signature_vars": {
+            "NAME": "Adam P. Strömbergsson-DeNora",
+            "TITLE": "Barrister & Solicitor",
+            "PHONE": "1 613 699 2127",
+            "ADDRESS": "7th floor - 1 Rideau St. Ottawa, ON. K1N 8S7",
+            "EMAIL": "adam@apstrom.ca"
+          }
+        }
+      }
+  - The LLM must provide accurate identity details; do not leave these fields blank or generic.
+
 ## MCP tools
 
 All tools are exposed via MCP (Streamable HTTP) at POST /mcp.