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postbridgeai/postbridge

v0.1.0MIT

Postal execution layer: quote, send, track, and prove physical letters from any AI agent.

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PostBridge Agent Plugin

Postal execution layer for AI agents: quote, send, track, and prove physical letters from any agent that supports the Agent Plugins open standard.

PostBridge turns a PDF (or generated document) into a physically mailed letter through print-and-mail providers, with carrier tracking and delivery proof. This plugin gives your AI agent that capability via PostBridge's hosted MCP server plus a set of Agent Skills playbooks.

Built on the Agent Plugins specification v1.0.0 — a portable package format for Agent Skills and MCP servers.

What's inside

ComponentLocationPurpose
plugin.jsonrootPlugin manifest (name postbridge, v0.1.0)
mcp.jsonrootRemote MCP server → https://api.postbridge.ai/mcp (Streamable HTTP)
skills/send-letterskills/Quote → confirm → send workflow, with 5-country address rules
skills/track-and-proofskills/Track mailed letters, retrieve delivery proof
skills/walletskills/Workspace wallet balance and top-up

MCP tools exposed

list_services, get_quote, send_letter, track_letter, get_proof, get_balance, top_up_wallet, list_letters.

Setup

This repository doubles as a Copilot CLI plugin marketplace — users can register it and install the plugin in one step:

copilot plugin marketplace add PostbridgeAI/postbridge-agent-plugin
copilot plugin install postbridge@postbridge-plugins

Or install directly from the repository / a local path with any Agent Plugins-compatible client.

PostBridge's MCP endpoint is subscription-backed and API-key authenticated. The plugin ships no credentials — your client injects the key.

  1. Create a workspace at postbridge.ai.
  2. Generate an API & MCP key in Settings → API & MCP (subscription-backed; usage consumes the workspace wallet).
  3. Install this plugin in your Agent Plugins-compatible client and configure the Authorization: Bearer <your-key> header / credential for the postbridge MCP server.

Per-client notes:

  • Cursor — install the plugin, then add your key as a plugin variable / MCP header under Plugins → Configure.
  • GitHub Copilot CLI — copilot plugin install from this repo or a marketplace entry, then set the MCP credential.
  • Codex / ChatGPT — connect the MCP server and supply the Bearer key in the auth step.

Safety model

  • Spend is explicit. send_letter and top_up_wallet move real money; the skills require explicit user confirmation of address, content, service, and price before any spend.
  • Server-side auth is fail-closed. The hosted MCP accepts only a subscription-backed SaaS API & MCP key (no UCAN/browser/x402/legacy keys).
  • No secrets in the package. The API key is never stored in plugin.json, mcp.json, env, or headers.
  • No fabricated proof. Tracking states and delivery proof are reported only as returned by the carrier.

Address support

The send-letter skill bundles a 5-country address reference (US, CA, FR, GB, DE) distilled from PostBridge's deterministic address parser. For other countries, the agent asks the user to confirm layout rather than guess.

Links

License

MIT — see LICENSE.