docs(sdk): explain automatic conversation title prompts

sdk/guides/agent-server/overview.mdx

@@ -57,6 +57,37 @@ Same interfaces as local:
  */}
 
 
+## Automatic conversation titles
+
+The Agent Server generates a title from the first user message when `autotitle`
+is enabled (the default). A configured `title_llm_profile` selects the title
+model; otherwise the server uses the agent's LLM, with message truncation as a
+fallback when generation fails.
+
+To customize the title-generation instructions, set `prompt` in the conversation
+creation request. Use `{conversation_content}` for the first user message and
+`{max_length}` for the output title-length limit. If the conversation placeholder
+is absent, the server appends the user message to the prompt. Empty or unset
+prompts retain the default instructions.
+
+```json
+{
+  "autotitle": true,
+  "prompt": "Use an action-first title of at most {max_length} characters. Describe the requested task without implying completion. Return only the title.\n\n{conversation_content}"
+}
+```
+
+These fields are part of the normal conversation creation request; include the
+required agent and workspace configuration as well. The title call receives the
+complete first user message and accepts prompts longer than 2,000 characters.
+Model context-window and provider request limits still apply. The default output
+title limit remains 50 characters. A custom prompt replaces the default user
+instructions, including their emoji requirement, so include any desired emoji
+rule explicitly.
+
+Title generation uses a separate LLM call. Skills loaded into the main agent's
+context do not automatically reach it; include relevant instructions in `prompt`.
+
 ## Architecture Overview
 
 Remote Agent Servers follow a simple three-part architecture: