Environment:Langchain ai Langchain Anthropic API Credentials
| Knowledge Sources | |
|---|---|
| Domains | Infrastructure, LLMs |
| Last Updated | 2026-02-11 14:00 GMT |
Overview
Environment credentials and SDK dependencies required for Anthropic Claude API integration via `langchain-anthropic`.
Description
The `langchain-anthropic` package provides the `ChatAnthropic` class for interacting with Claude models. It requires an Anthropic API key and depends on `anthropic >= 0.78.0`. The package supports tool calling, structured output, streaming, and Anthropic-specific features like prompt caching and built-in tools (web fetch, code execution, computer use).
Usage
Required for any workflow that uses Anthropic Claude models. This includes chat completions, tool calling, structured output, and streaming with Claude. Some features require specific beta headers managed via `_TOOL_TYPE_TO_BETA` mapping.
System Requirements
| Category | Requirement | Notes |
|---|---|---|
| Python | >= 3.10.0, < 4.0.0 | Same as core |
| Network | HTTPS outbound to api.anthropic.com | Or custom base URL |
| SDK | anthropic >= 0.78.0, < 1.0.0 | Official Anthropic Python SDK |
Dependencies
Python Packages
- `langchain-core` >= 1.2.11, < 2.0.0
- `anthropic` >= 0.78.0, < 1.0.0
- `pydantic` >= 2.7.4, < 3.0.0
Credentials
The following environment variables must be set:
Required:
- `ANTHROPIC_API_KEY`: Anthropic API key for authentication.
Optional:
- `ANTHROPIC_API_URL` or `ANTHROPIC_BASE_URL`: Custom API base URL (default: `https://api.anthropic.com`).
- `ANTHROPIC_PROXY`: Proxy URL for Anthropic connections.
Integration Testing Only:
- `ANTHROPIC_FILES_API_IMAGE_ID`: Image file ID for file search tests.
- `ANTHROPIC_FILES_API_PDF_ID`: PDF file ID for file search tests.
Quick Install
pip install langchain-anthropic>=1.3.3
# Set API key
export ANTHROPIC_API_KEY="sk-ant-..."
Code Evidence
Fallback max output tokens from `libs/partners/anthropic/langchain_anthropic/chat_models.py:93`:
_FALLBACK_MAX_OUTPUT_TOKENS: Final[int] = 4096
Beta header mapping for special tools from `libs/partners/anthropic/langchain_anthropic/chat_models.py:134-148`:
_TOOL_TYPE_TO_BETA: dict[str, str] = {
"web_fetch_20250910": "web-fetch-2025-09-10",
"code_execution_20250522": "code-execution-2025-05-22",
"mcp_toolset": "mcp-client-2025-11-20",
"memory_20250818": "context-management-2025-06-27",
"computer_20250124": "computer-use-2025-01-24",
}
Client URL detection from `libs/partners/anthropic/langchain_anthropic/_client_utils.py:57-76`:
base_url = os.environ.get("ANTHROPIC_BASE_URL", "https://api.anthropic.com")
Common Errors
| Error Message | Cause | Solution |
|---|---|---|
| `ValueError: Did not find anthropic_api_key` | ANTHROPIC_API_KEY not set | `export ANTHROPIC_API_KEY="sk-ant-..."` or pass `api_key=` parameter |
| `anthropic.AuthenticationError: 401` | Invalid API key | Verify API key at console.anthropic.com |
| `anthropic.BadRequestError: max_tokens required` | max_tokens not set and model profile missing | Set `max_tokens` explicitly or ensure model profiles are up to date |
Compatibility Notes
- Beta Features: Some tool types (web fetch, code execution, MCP, computer use) require versioned beta headers automatically injected by the SDK.
- Fallback Tokens: When model profile is unavailable, `max_output_tokens` defaults to 4096.
- Proxy Support: The `ANTHROPIC_PROXY` env var configures httpx proxy for corporate network access.