feat(tools): add Brevo transactional email and SMS integration

[Hustple]

Description

Adds a Brevo integration that enables Hive agents to send transactional emails, SMS messages, and manage contacts via the Brevo API.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)

Related Issues

Fixes #5127

Changes Made

• Add tools/src/aden_tools/tools/brevo_tool/brevo_tool.py with 6 MCP tools: brevo_send_email, brevo_send_sms, brevo_create_contact, brevo_get_contact, brevo_update_contact, brevo_get_email_stats
• Add tools/src/aden_tools/tools/brevo_tool/__init__.py with register_tools export
• Add tools/src/aden_tools/tools/brevo_tool/README.md with setup instructions and usage examples
• Add tools/src/aden_tools/credentials/brevo.py with CredentialSpec for BREVO_API_KEY
• Add tools/tests/tools/test_brevo_tool.py with 34 unit tests
• Register brevo_tool in tools/src/aden_tools/tools/__init__.py
• Register BREVO_CREDENTIALS in tools/src/aden_tools/credentials/__init__.py

Tool Summary

Tool	Purpose
brevo_send_email	Send a transactional email with HTML content
brevo_send_sms	Send a transactional SMS to a phone number
brevo_create_contact	Create a new contact in Brevo
brevo_get_contact	Retrieve contact details by email
brevo_update_contact	Update an existing contact's attributes
brevo_get_email_stats	Get delivery status for a sent email

Environment Variables

Variable	Required	Description
BREVO_API_KEY	Yes	Brevo API key from Settings → API Keys

Setup Instructions

1. Sign up at https://www.brevo.com (free tier available - 300 emails/day)
2. Go to Settings → API Keys → Generate a new API key
3. Set BREVO_API_KEY environment variable or configure via credential store
4. Verify your sender email address in Brevo before sending emails

Testing

Verified import success:

uv run python3 -c "from src.aden_tools.tools.brevo_tool.brevo_tool import register_tools; print('Import OK!')"
# Output: Import OK!

Verified all 6 tools register correctly:

uv run python3 -c "
from fastmcp import FastMCP
from src.aden_tools.tools import register_all_tools
mcp = FastMCP('test')
tools = register_all_tools(mcp)
brevo_tools = [t for t in tools if t.startswith('brevo')]
print(brevo_tools)
"
# Output: ['brevo_send_email', 'brevo_send_sms', 'brevo_create_contact',
#          'brevo_get_contact', 'brevo_update_contact', 'brevo_get_email_stats']

34 unit tests pass:

uv run pytest tests/tools/test_brevo_tool.py -v
# Output: 34 passed in 2.45s

Tests cover:

• Credential handling (missing credentials error)
• brevo_send_email — success, input validation, auth error, timeout
• brevo_send_sms — success, phone format validation, content length, timeout
• brevo_create_contact — success, list_ids parsing, validation, timeout
• brevo_get_contact — success, not found, validation, timeout
• brevo_update_contact — success, list_ids parsing, validation, timeout
• brevo_get_email_stats — success, empty message_id, not found, timeout
• Tool registration — all 6 tools, with and without credentials

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes