Bring Direct Mail
to Pydantic AI
Learn how to connect Lob to Pydantic AI and start using 9 AI agent tools in minutes. Fully managed, enterprise secure, and ready to use without writing a single line of code.
What is the Lob MCP Server?
Connect your Lob account to any AI agent and manage direct mail through natural conversation.
What you can do
- Letter Sending — Create and send letters with PDF or HTML content
- Postcard Campaigns — Send postcards with front/back designs
- Check Printing — Create and mail checks with payment details
- Address Verification — Verify and standardize US addresses
- Template Management — Browse and manage mail templates
- Delivery Tracking — Track mail pieces through the postal system
How it works
1. Subscribe to this server
2. Enter your Lob API Key (test or live)
3. Start sending mail from Claude, Cursor, or any MCP-compatible client
Who is this for?
- Marketing — run direct mail campaigns with postcards and letters
- Finance — automate check printing and mailing
- Operations — verify addresses and track mail delivery
Built-in capabilities (9)
Suggest address completions
Send a physical check
Supports certified mail and custom inserts. Send a physical letter
Supports HTML or PDF for front and back. Send a physical postcard
Track a mail piece
List sent letters
List sent postcards
Verify an international address
Verify a US address
Why Pydantic AI?
Pydantic AI validates every Lob tool response against typed schemas, catching data inconsistencies at build time. Connect 9 tools through Vinkius and switch between OpenAI, Anthropic, or Gemini without changing your integration code. full type safety, structured output guarantees, and dependency injection for testable agents.
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Full type safety: every MCP tool response is validated against Pydantic models, catching data inconsistencies before they reach your application
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Model-agnostic architecture. switch between OpenAI, Anthropic, or Gemini without changing your Lob integration code
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Structured output guarantee: Pydantic AI ensures tool results conform to defined schemas, eliminating runtime type errors
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Dependency injection system cleanly separates your Lob connection logic from agent behavior for testable, maintainable code
Lob in Pydantic AI
Lob and 3,400+ other MCP servers. One platform. One governance layer.
Teams that connect Lob to Pydantic AI through Vinkius don't need to source, host, or maintain individual MCP servers. Every tool call runs inside a hardened runtime with credential isolation, DLP, and a signed audit chain.
Raw MCP | Vinkius | |
|---|---|---|
| Server catalog | Find and host yourself | 3,400+ managed |
| Infrastructure | Self-hosted | Sandboxed V8 isolates |
| Credential handling | Plaintext in config | Vault + runtime injection |
| Data loss prevention | None | Configurable DLP policies |
| Kill switch | None | Global instant shutdown |
| Financial circuit breakers | None | Per-server limits + alerts |
| Audit trail | None | Ed25519 signed logs |
| SIEM log streaming | None | Splunk, Datadog, Webhook |
| Honeytokens | None | Canary alerts on leak |
| Custom domains | Not applicable | DNS challenge verified |
| GDPR compliance | Manual effort | Automated purge + export |
Why teams choose Vinkius for Lob in Pydantic AI
The Lob MCP Server runs on Vinkius-managed infrastructure inside AWS — a purpose-built runtime with per-request V8 isolates, Ed25519 signed audit chains, and sub-40ms cold starts. All 9 tools execute in hardened sandboxes optimized for native MCP execution.
Your AI agents in Pydantic AI only access the data you authorize, with DLP that blocks sensitive information from ever reaching the model, kill switch for instant shutdown, and up to 60% token savings. Enterprise-grade infrastructure, zero maintenance.
* Every MCP server runs on Vinkius-managed infrastructure inside AWS - a purpose-built runtime with per-request V8 isolates, Ed25519 signed audit chains, and sub-40ms cold starts optimized for native MCP execution. See our infrastructure
How Vinkius secures
Lob for Pydantic AI
Every tool call from Pydantic AI to the Lob MCP Server is protected by DLP redaction, cryptographic audit chains, V8 sandbox isolation, kill switch, and financial circuit breakers.
Frequently asked questions
Can I send letters and postcards through the AI agent?
Yes. Create and send letters with PDF/HTML content and postcards with custom designs. Track delivery through the postal system.
Does Lob use Basic Auth?
Yes. Lob uses HTTP Basic Auth with the API Key as username (no password) against api.lob.com/v1.
Can I verify US addresses?
Yes. Verify and standardize US addresses with CASS certification. Returns deliverability status, corrected addresses, and coordinates.
How does Pydantic AI discover MCP tools?
Create an MCPServerHTTP instance with the server URL. Pydantic AI connects, discovers all tools, and generates typed Python interfaces automatically.
Does Pydantic AI validate MCP tool responses?
Yes. When you define result types as Pydantic models, every tool response is validated against the schema. Invalid data raises a clear error instead of silently corrupting your pipeline.
Can I switch LLM providers without changing MCP code?
Absolutely. Pydantic AI abstracts the model layer. your Lob MCP integration works identically with OpenAI, Anthropic, Google, or any supported provider.
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Update: pip install --upgrade pydantic-ai