How to Use the Lob MCP in LlamaIndex

Q: Can LlamaIndex query past Lob mailings using vector search?

Yes. Your agent calls listpostcards or listletters, indexes the text contents, and stores them in a vector database. You can then run semantic queries across your physical mail history.

Q: How does Lob handle international addresses within LlamaIndex?

The agent uses verifyintladdress to validate global locations before writing them to your index. This ensures your customer database remains clean and accurate for global campaigns.

Q: Can I limit which tools the LlamaIndex agent can access?

Yes. You can use the allowedtools filter during setup to restrict the agent. For example, you can allow address verification while blocking check creation on this MCP instance.

Index your physical mail history directly into LlamaIndex to query delivery tracking and customer addresses with semantic search.

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Index physical mail tracking into LlamaIndex

`get_mail_tracking` pulls delivery data that your agent indexes directly into your vector store using this MCP Server. This turns offline mail status into searchable knowledge. Users can query the system about delivery dates without searching through individual receipts. Your agent accesses past mailings by pulling data from `list_letters` and `list_postcards`. LlamaIndex processes these outputs to build a historical record of customer touchpoints. This ensures your RAG pipeline has access to physical mail events alongside digital logs.

Verify address data before indexing

`verify_us_address` cleans up your contact databases before you build your search index. The agent runs this tool to ensure address strings are standardized. This validation step prevents duplicate records across your MCP integrations. For global users, `verify_intl_address` standardizes international locations. The `autocomplete_address` tool helps users input correct details during data entry. Clean address data leads to more accurate retrieval during vector search queries.

Trigger check and letter creation from search queries

`create_check` allows your system to issue physical checks based on retrieval-augmented decisions. When a query identifies an outstanding balance, the agent triggers the payment tool. This links your structured data search directly to physical financial actions. You can also use `create_letter` to send formal notifications when specific documents are retrieved. The agent formats the letter's custom inserts using the retrieved text. This closes the gap between document search and physical execution.

Setup guide

Set up Lob MCP in LlamaIndex

Prerequisites

Python 3.10+ installed
llama-index-tools-mcp package
Active Vinkius subscription with a valid endpoint token

1

Install dependencies
Run pip install llama-index-tools-mcp llama-index-llms-openai. The MCP tools package provides BasicMCPClient and McpToolSpec.
2

Connect with BasicMCPClient
Point BasicMCPClient to your Vinkius endpoint URL. Replace [YOUR_TOKEN_HERE] with your token from cloud.vinkius.com. Supports SSE and Streamable HTTP transports.
3

Convert to LlamaIndex tools
Call mcp_tool_spec.to_tool_list_async() to convert all Lob MCP tools into native FunctionTool objects that any LlamaIndex agent can use.
4

Run with any LLM
Create a FunctionAgent with the tools and your preferred LLM. Swap OpenAI for Anthropic, Gemini, or any LlamaIndex-supported provider.

agent.py

from llama_index.tools.mcp import BasicMCPClient, McpToolSpec
from llama_index.core.agent.workflow import FunctionAgent
from llama_index.llms.openai import OpenAI

# Connect to the MCP
mcp_client = BasicMCPClient(
    "https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp"
)
mcp_tool_spec = McpToolSpec(client=mcp_client)

# Convert MCP tools to LlamaIndex tools
tools = await mcp_tool_spec.to_tool_list_async()

# Create and run the agent
agent = FunctionAgent(
    tools=tools,
    llm=OpenAI(model="gpt-4o"),
    system_prompt="You have access to Lob tools.",
)
response = await agent.run("List recent Lob data")

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Independent Platform Disclaimer: Vinkius is an independent platform and is not affiliated with, endorsed by, sponsored by, verified by, or otherwise authorized by Lob. All third-party trademarks, logos, and brand names are the property of their respective owners. Their use on this website is strictly for informational purposes to identify service compatibility and interoperability.

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Common questions about Lob MCP in LlamaIndex

Install llama-index-tools-mcp and instantiate the BasicMCPClient. Convert the server tools using McpToolSpec and pass them to your FunctionAgent to start mailing.

Yes. Your agent calls `list_postcards` or `list_letters`, indexes the text contents, and stores them in a vector database. You can then run semantic queries across your physical mail history.

The agent uses `verify_intl_address` to validate global locations before writing them to your index. This ensures your customer database remains clean and accurate for global campaigns.

Yes. You can use the allowed_tools filter during setup to restrict the agent. For example, you can allow address verification while blocking check creation on this MCP instance.

All address strings and check details are processed in ephemeral V8 isolates. Vinkius does not log or retain the PII passing through the API, keeping your customer records compliant.

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