moss-anthropic

MOSS signing integration for Anthropic SDK (Claude). Unsigned output is broken output.

Installation

pip install moss-anthropic

Quick Start

Sign tool use, responses, and text blocks from Claude:

from anthropic import Anthropic
from moss_anthropic import sign_tool_use, sign_response, sign_text

client = Anthropic()

# Get a response with tool use
response = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=1024,
    messages=[{"role": "user", "content": "What's the weather?"}],
    tools=[{"name": "get_weather", "description": "Get weather", ...}]
)

# Sign the full response
result = sign_response(response, agent_id="weather-bot")
print(f"Signed: {result.signature[:20]}...")

# Sign individual tool use blocks
for block in response.content:
    if block.type == "tool_use":
        result = sign_tool_use(block, agent_id="weather-bot")

Enterprise Mode

Set MOSS_API_KEY for automatic policy evaluation:

import os
os.environ["MOSS_API_KEY"] = "your-api-key"

from moss_anthropic import sign_tool_use, enterprise_enabled

print(f"Enterprise: {enterprise_enabled()}")  # True

result = sign_tool_use(
    tool_use_block,
    agent_id="finance-bot",
    context={"user_id": "u123"}
)

if result.blocked:
    print(f"Blocked by policy: {result.policy.reason}")

Verification

from moss_anthropic import verify_envelope

verify_result = verify_envelope(result.envelope)
if verify_result.valid:
    print(f"Signed by: {verify_result.subject}")

All Functions

Enterprise Features

Links

• moss-sdk - Core MOSS SDK
• mosscomputing.com - Project site

License

This package is licensed under the Business Source License 1.1.

• Free for evaluation, testing, and development
• Free for non-production use
• Production use requires a MOSS subscription
• Converts to Apache 2.0 on January 25, 2030