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

# Ampersend integration

> Enable LangChain agents to pay for and use remote AI agent services.

[Ampersend](https://ampersend.ai) enables LangChain agents to pay for and use remote AI agent services. Payments are handled transparently via the [x402](https://www.x402.org/) protocol, with [A2A](https://google.github.io/A2A/) as the communication layer.

## Overview

### Integration details

| Class        | Package               | Serializable | JS support |                                              Version                                              |
| :----------- | :-------------------- | :----------: | :--------: | :-----------------------------------------------------------------------------------------------: |
| `A2AToolkit` | `langchain-ampersend` |       ❌      |      ❌     | ![PyPI - Version](https://img.shields.io/pypi/v/langchain-ampersend?style=flat-square\&label=%20) |

### Tool features

1. **a2a\_get\_agent\_details** - Get capabilities of the remote agent
2. **a2a\_send\_message** - Send messages to the remote agent (payments handled automatically)

### Key features

* **Spend controls**: Pluggable payment authorization with limits and policies
* **Transparent payments**: x402 protocol handles payment negotiation automatically

***

## Setup

### Installation

Install the `langchain-ampersend` package:

<CodeGroup>
  ```python pip theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}}
  pip install -U langchain-ampersend
  ```

  ```python uv theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}}
  uv add langchain-ampersend
  ```
</CodeGroup>

### Credentials

The toolkit requires a session key and smart account address, which you can obtain from the [Ampersend dashboard](https://app.ampersend.ai).

```python Set up credentials icon="key" theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}}
import os

SESSION_KEY = os.environ.get("AMPERSEND_SESSION_KEY")  # 0x...
SMART_ACCOUNT_ADDRESS = os.environ.get("AMPERSEND_SMART_ACCOUNT_ADDRESS")  # 0x...
```

***

## Instantiation

```python Initialize toolkit icon="robot" theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}}
from langchain_ampersend import (
    A2AToolkit,
    AmpersendTreasurer,
    ApiClient,
    ApiClientOptions,
    SmartAccountConfig,
    SmartAccountWallet,
)

# Setup wallet
wallet = SmartAccountWallet(
    config=SmartAccountConfig(
        session_key=SESSION_KEY,
        smart_account_address=SMART_ACCOUNT_ADDRESS,
    )
)

# Setup treasurer
treasurer = AmpersendTreasurer(
    api_client=ApiClient(
        options=ApiClientOptions(
            base_url="https://api.ampersend.ai",
            session_key_private_key=SESSION_KEY,
        )
    ),
    wallet=wallet,
)

# Create toolkit
toolkit = A2AToolkit(
    remote_agent_url="https://agent.example.com",
    treasurer=treasurer,
)

await toolkit.initialize()
```

***

## Invocation

Send a message to the remote agent:

```python Send message icon="message" theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}}
tools = toolkit.get_tools()
send_tool = tools[1]  # a2a_send_message
response = await send_tool.ainvoke({"message": "Analyze the sales trends in Q4"})
print(response)
```

***

## Use within an agent

```python Create agent icon="robot" theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}}
from langchain.agents import create_agent
from langchain_anthropic import ChatAnthropic

# Initialize the LLM
llm = ChatAnthropic(model="claude-sonnet-4-20250514")

# Get tools from the toolkit
tools = toolkit.get_tools()

# Create the agent
agent = create_agent(llm, tools)
```

Example usage:

```python Run agent icon="rocket" theme={"theme":{"light":"catppuccin-latte","dark":"catppuccin-mocha"}}
result = await agent.ainvoke({
    "messages": [("user", "What can this agent do, and then ask it to analyze recent trends")]
})

# The agent will call the remote agent and handle payments automatically
```

***

## How payments work

When the remote agent requires payment (HTTP 402), the toolkit:

1. Receives the payment requirement
2. Calls the treasurer to authorize the payment
3. Signs the payment with the configured wallet
4. Retries the request with the payment attached

This is transparent to your LangChain agent.

The `AmpersendTreasurer` provides managed payment sessions with spend limits and analytics. Alternative treasurer implementations are available in `ampersend_sdk`.

***

## API reference

* [Ampersend Documentation](https://docs.ampersend.ai)
* [x402 Protocol Specification](https://www.x402.org/)

***

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