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Lob MCP Integration for LangChain

Connect Lob to LangChain through the local KosmoKrator MCP gateway with scoped tools, credentials, and write policy.

7 functions 5 read 2 write API key auth
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Connect Lob to LangChain

Bridge LangChain agents to local KosmoKrator integration tools through MCP or headless CLI calls.

Use the MCP gateway when the agent should discover tools, or wrap kosmo integrations:call for fixed chains. The gateway is local, scoped to this integration, and starts with --write=deny so LangChain can inspect read-capable tools without receiving write access by default.

Lob MCP Config for LangChain

Keep the gateway scoped to the integration and operation class needed by the chain.

{
  "mcpServers": {
    "kosmokrator-lob": {
      "type": "stdio",
      "command": "kosmo",
      "args": [
        "mcp:serve",
        "--integration=lob",
        "--write=deny"
      ]
    }
  }
}

Run the Gateway Manually

kosmokrator mcp:serve --integration=lob --write=deny

Why Use KosmoKrator Here

Scoped tools

Expose only Lob instead of a broad multi-service tool list.

Local credentials

Reuse credentials already configured for the KosmoKrator CLI and Lua runtime.

Write policy

Start read-only, then opt into ask or allow for trusted workspaces.

Lob Tools Visible to LangChain

LangChain sees stable MCP tool names generated from the Lob integration catalog.

MCP toolSource functionTypeDescription
integration__lob__lob_list_letters lob.lob_list_letters Read List letters with pagination. Returns a page of letter objects sorted by creation date (newest first).
integration__lob__lob_get_letter lob.lob_get_letter Read Retrieve details of a specific letter by its Lob ID, including delivery status, tracking info, and the letter URL.
integration__lob__lob_create_letter lob.lob_create_letter Write Create and send a letter via Lob. Provide recipient and sender addresses (as address IDs or inline address objects), plus an HTML file or template ID for the letter content.
integration__lob__lob_list_postcards lob.lob_list_postcards Read List postcards with pagination. Returns a page of postcard objects sorted by creation date (newest first).
integration__lob__lob_get_postcard lob.lob_get_postcard Read Retrieve details of a specific postcard by its Lob ID, including delivery status, tracking info, and thumbnails.
integration__lob__lob_create_postcard lob.lob_create_postcard Write Create and send a postcard via Lob. Provide recipient and sender addresses (as address IDs or inline address objects), plus HTML or template IDs for the front and back.
integration__lob__lob_get_current_user lob.lob_get_current_user Read List saved addresses in the Lob account. Returns all verified addresses that can be used as sender or recipient for letters and postcards.

Related Lob Pages

Lob CLIUse direct JSON commands instead of MCP discovery. Lob MCPFull gateway reference and MCP tool names. KosmoKrator for LangChainClient-level gateway setup.