> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lithoblocks.com/llms.txt
> Use this file to discover all available pages before exploring further.

# CrewAI

> Use LithoBlocks templates from CrewAI agents and tasks.

Use LithoBlocks with [CrewAI](https://www.crewai.com/) so your agents can send Slack messages via templates. An agent (or a dedicated "notifier" agent) uses a tool to call the LithoBlocks API with a template ID and payload. You get deterministic messages and far fewer tokens because the LLM does not generate Block Kit JSON. The resulting LLM savings help offset LithoBlocks cost, with net cost reduction at higher volumes.

## Prerequisites

* LithoBlocks API key and at least one template
* [Connecting Slack](/connecting-slack) for your LithoBlocks workspace
* CrewAI installed (`pip install crewai` or equivalent)

## Why use LithoBlocks with CrewAI

* **Deterministic messages** — The agent picks a template and data; the tool sends it. No Block Kit in the prompt.
* **Lower LLM cost** — The agent outputs only `template_id` and a small payload; the tool does the HTTP call. LLM savings help offset LithoBlocks cost; at higher volumes, net cost reduction.
* **Consistency** — Same layout every time; fewer malformed blocks. A dedicated "Notifier" agent can own the tool and send to Slack on behalf of other agents.

## Implementing the tool

Define a CrewAI tool that accepts `template_id` and `payload` (mapped to API field `data`), then POSTs to the LithoBlocks API.

```python theme={null}
import os
from typing import Optional

import requests
from crewai.tools import tool

LITHOBLOCKS_API_KEY = os.environ.get("LITHOBLOCKS_API_KEY")
BASE_URL = "https://api.lithoblocks.com"

@tool("Send Slack message")
def send_slack_message(template_id: str, payload: dict, channel_id: Optional[str] = None) -> str:
    """Send a Slack message using a LithoBlocks template. Use when the user or another agent wants to notify someone in Slack.
    template_id: The LithoBlocks template ID (e.g. from your dashboard).
    payload: JSON object matching the template's placeholders (e.g. {"user": {"name": "Alice"}, "message": "Hello"}).
    channel_id: Optional Slack channel ID for send (see API reference for other destinations).
    """
    url = f"{BASE_URL}/v1/templates/send"
    headers = {
        "Authorization": f"Bearer {LITHOBLOCKS_API_KEY}",
        "Content-Type": "application/json",
    }
    body = {"template_id": template_id, "data": payload}
    if channel_id:
        body["channel_id"] = channel_id
    response = requests.post(url, json=body, headers=headers)
    if response.ok:
        return f"Message sent successfully: {response.json().get('message_ts', 'ok')}"
    return f"Failed to send message: {response.status_code} {response.text}"
```

For **compile** (get blocks without sending), use `POST /v1/templates/compile` with body `{"template_id": "...", "data": {...}}`. See the [API reference](/api-reference/introduction) for request/response shapes.

## Using the tool in an agent or task

Assign the tool to an agent (e.g. "Notifier" or "Researcher"). The agent can send Slack messages by calling the tool with `template_id` and `payload`.

```python theme={null}
from crewai import Agent, Task, Crew

notifier = Agent(
    role="Notifier",
    goal="Send Slack messages when the user or other agents need to notify someone.",
    backstory="You use LithoBlocks templates to send structured Slack messages.",
    tools=[send_slack_message],
    verbose=True,
)

task = Task(
    description="Send a Slack message to #general saying the report is ready.",
    agent=notifier,
)

crew = Crew(agents=[notifier], tasks=[task])
result = crew.kickoff()
```

The agent will call `send_slack_message` with the appropriate `template_id` and `payload` for your template.

## Next steps

<CardGroup cols={2}>
  <Card title="AI agents overview" icon="robot" href="/guides/ai-agents-overview">
    Why templates and agents fit together.
  </Card>

  <Card title="API reference" icon="code" href="/api-reference/introduction">
    Endpoints, auth, and parameters.
  </Card>

  <Card title="Placeholders" icon="code" href="/guides/templates-placeholders">
    Template data shape and syntax.
  </Card>
</CardGroup>