Anthropic Python SDK

0.84.0 verified Mon May 11 auth: no python install: verified quickstart: verified

Official Python SDK for the Anthropic API providing access to Claude models. Current version is 0.84.0 (Feb 2026). Releases approximately weekly. Two separate packages exist: anthropic (core SDK) and claude-agent-sdk-python (agent workflows).

pip install anthropic

Common errors

error ModuleNotFoundError: No module named 'anthropic' ↓

cause The 'anthropic' package is not installed in the Python environment.

fix

Install the package using 'pip install anthropic'.

error ImportError: cannot import name 'Anthropic' from 'anthropic' ↓

cause The import statement is incorrect; 'Anthropic' is not a valid import from the 'anthropic' package.

fix

Use 'from anthropic import AnthropicClient' instead.

error AttributeError: module 'anthropic' has no attribute 'Anthropic' ↓

cause The 'Anthropic' class does not exist in the 'anthropic' module.

fix

Instantiate the client with 'client = anthropic.AnthropicClient()'.

error TypeError: __init__() missing 1 required positional argument: 'api_key' ↓

cause The 'AnthropicClient' class requires an 'api_key' argument during initialization.

fix

Initialize with 'client = anthropic.AnthropicClient(api_key="your_api_key")'.

error ValueError: Invalid API key provided ↓

cause The provided API key is incorrect or malformed.

fix

Ensure the API key is correct and properly formatted.

Warnings

breaking anthropic.Client() is removed. Use anthropic.Anthropic() instead. ↓

fix client = Anthropic(api_key=os.environ.get('ANTHROPIC_API_KEY'))

gotcha SDK releases weekly. Pin your version in production or expect frequent behaviour changes. ↓

fix Pin with anthropic==0.84.0 in requirements.txt

gotcha message.content is a list, not a string. Access text via message.content[0].text. ↓

fix print(message.content[0].text) not print(message.content)

gotcha max_tokens is required. No default value. Omitting raises a validation error. ↓

fix Always pass max_tokens=1024 or appropriate value

deprecated claude-agent-sdk-python no longer requires Claude Code to be installed separately. It is bundled. ↓

fix Remove any separate Claude Code install steps from your setup.

breaking The package `claude-agent-sdk` is not a valid PyPI package and cannot be found. If you are trying to install the main Anthropic SDK, use `anthropic`. If you are looking for an agent-specific SDK, you might be looking for `claude-agent-sdk-python`. ↓

fix Replace `claude-agent-sdk` with `anthropic` or `claude-agent-sdk-python` in your requirements/install commands.

breaking Failed to authenticate due to missing API key. Ensure `api_key` is passed during client initialization or set the `ANTHROPIC_API_KEY` environment variable. ↓

fix client = Anthropic(api_key=os.environ.get('ANTHROPIC_API_KEY'))

Install

pip install claude-agent-sdk

npm install @anthropic-ai/sdk

Install compatibility verified last tested: 2026-05-11

python os / libc variant status wheel install import disk

3.10 alpine (musl) anthropic - - 3.29s 39.8M

3.10 alpine (musl) claude-agent-sdk - - - -

3.10 slim (glibc) anthropic - - 2.37s 39M

3.10 slim (glibc) claude-agent-sdk - - - -

3.11 alpine (musl) anthropic - - 4.27s 43.2M

3.11 alpine (musl) claude-agent-sdk - - - -

3.11 slim (glibc) anthropic - - 3.65s 42M

3.11 slim (glibc) claude-agent-sdk - - - -

3.12 alpine (musl) anthropic - - 3.97s 34.6M

3.12 alpine (musl) claude-agent-sdk - - - -

3.12 slim (glibc) anthropic - - 3.91s 34M

3.12 slim (glibc) claude-agent-sdk - - - -

3.13 alpine (musl) anthropic - - 3.56s 34.3M

3.13 alpine (musl) claude-agent-sdk - - - -

3.13 slim (glibc) anthropic - - 3.70s 33M

3.13 slim (glibc) claude-agent-sdk - - - -

3.9 alpine (musl) anthropic - - 3.19s 39.1M

3.9 alpine (musl) claude-agent-sdk - - - -

3.9 slim (glibc) anthropic - - 2.94s 38M

3.9 slim (glibc) claude-agent-sdk - - - -

Imports

Anthropic
wrong
```
import anthropic; anthropic.Client(api_key=...)
```
correct
```
from anthropic import Anthropic
```
anthropic.Client is the old pre-0.3 API. Removed. Always use Anthropic() class.
AsyncAnthropic
wrong
```
import anthropic; anthropic.AsyncClient()
```
correct
```
from anthropic import AsyncAnthropic
```
Use AsyncAnthropic for async contexts, not the legacy async client.

Quickstart verified last tested: 2026-05-11

Minimal message call using the Anthropic SDK 0.84.x.

from anthropic import Anthropic

client = Anthropic()  # reads ANTHROPIC_API_KEY from env
message = client.messages.create(
    model='claude-opus-4-6',
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Hello, Claude"}
    ]
)
print(message.content[0].text)