feat: add Twilio plugin

[saoudrizwan]

Twilio

Adds a Twilio plugin for Cline users building messaging, voice, verification, support, and email workflows with Twilio and SendGrid.

The plugin bundles the Twilio and SendGrid workflow skill pack so Cline can reason through product selection, account setup, SMS/WhatsApp/RCS sending, Voice and TwiML patterns, Verify flows, Lookup checks, regulatory onboarding, webhook handling, Conversation Orchestrator, Conversation Intelligence, Customer Memory, SendGrid sending, deliverability, inbound parse, suppressions, and event webhooks.

Cline Primitives

• Skills: 55 local Twilio and SendGrid skills, including the supporting icon assets from the skill pack. Source agent-profile files are intentionally omitted because they do not map to Cline's plugin surface.
• MCP: registers twilio-docs as a streamable HTTP MCP server at https://mcp.twilio.com/docs. This is a documentation MCP for semantic Twilio docs search and API operation/schema retrieval, and it does not require authentication.
• Rule: adds twilio-safety, which tells Cline to treat credentials, phone numbers, email addresses, message bodies, recordings, transcripts, verification codes, webhook payloads, and customer data as sensitive, and to require explicit approval before live sends, calls, OTPs, compliance changes, number purchases/releases, credential changes, or production traffic changes.

Requirements

Using the docs MCP only requires network access to Twilio's public MCP endpoint. Live Twilio work still requires the user's Twilio account and credentials such as TWILIO_ACCOUNT_SID and TWILIO_AUTH_TOKEN. SendGrid workflows require a SendGrid account and SENDGRID_API_KEY.

Channel-specific work may also require valid sender identities, phone numbers, WhatsApp senders, regulatory registrations, webhook URLs, verified domains, and proof of user consent. The plugin does not collect or configure those during install.

Trust Boundaries

Installing the plugin only registers the unauthenticated Twilio docs MCP and local skills. It does not send messages, place calls, create Twilio or SendGrid resources, read account data, or contact Twilio or SendGrid APIs with user credentials during setup.

The copied skills include live-operation examples, so the Cline safety rule and the edited quick-start notes make the approval boundary explicit before buying numbers, logging in with the CLI, creating Verify services, sending OTPs, sending messages, or touching production traffic.

[saoudrizwan]

Closing this plugin PR for now because this cleanup pass is limiting plugin marketplace PRs to plugins that only bundle MCP servers and/or skills. This PR includes additional plugin primitive(s): rules.

Those primitives may still be useful, but we are keeping this batch scoped to MCP and skill distribution.