> ## Documentation Index
> Fetch the complete documentation index at: https://agno-v2.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Anthropic Append Trailing User Message

> Append a trailing user turn with append_trailing_user_message when a Claude 4.6 conversation ends on an assistant message.

Claude 4.6+ does not support assistant message prefill. Enable `append_trailing_user_message` to append a trailing user turn when the conversation ends with an assistant message (e.g. during reasoning).

```python append_trailing_user_message.py theme={null}
"""
Anthropic Append Trailing User Message
======================================

Claude 4.6+ does not support assistant message prefill. Enable
`append_trailing_user_message` to append a trailing user turn when the
conversation ends with an assistant message (e.g. during reasoning).

Use `trailing_user_message_content` to customise the appended text (defaults to "continue").

Note: Claude 4.6+ models auto-detect and enable this flag automatically.
"""

from agno.agent import Agent
from agno.models.anthropic import Claude

# ---------------------------------------------------------------------------
# Create Agent
# ---------------------------------------------------------------------------

agent = Agent(
    model=Claude(id="claude-sonnet-4-6", append_trailing_user_message=True),
    reasoning_model=Claude(id="claude-opus-4-7"),
    markdown=True,
)

# With custom trailing content
agent_custom = Agent(
    model=Claude(
        id="claude-sonnet-4-6",
        append_trailing_user_message=True,
        trailing_user_message_content=".",
    ),
    reasoning_model=Claude(id="claude-opus-4-7"),
    markdown=True,
)

# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    agent.print_response("What is 15 + 27?")
    agent_custom.print_response("What is 15 + 27?")
```

## Run the Example

<Snippet file="create-venv-step.mdx" />

**1. Install dependencies**

```bash theme={null}
uv pip install -U agno anthropic
```

**2. Export your Anthropic API key**

```bash Mac/Linux theme={null}
export ANTHROPIC_API_KEY="your_anthropic_api_key_here"
```

```bash Windows theme={null}
$Env:ANTHROPIC_API_KEY="your_anthropic_api_key_here"
```

**3. Run the example**

Save the code above as `append_trailing_user_message.py`, then run:

```bash theme={null}
python append_trailing_user_message.py
```

Full source: [cookbook/90\_models/anthropic/append\_trailing\_user\_message.py](https://github.com/agno-agi/agno/blob/v3.0.4/cookbook/90_models/anthropic/append_trailing_user_message.py)


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