3LT Letter Mail
Give AI assistants hands: send real USPS letters via MCP.
Should I use this
Quality & Safety
Based on automated analysis of tool definitions and protocol compliance.
Context Cost
This is the approximate number of tokens consumed each time the server's tools are loaded into a model's context. Higher counts reduce the attention available for other tasks.
Install
One-Click Install
Add this to your `claude_desktop_config.json` file:
{
"mcpServers": {
"3lt-letter-mail": {
"url": "https://3lgrouptechnology.com/mcp"
}
}
}Remote endpoints
https://3lgrouptechnology.com/mcpstreamable-httpWhat it can do
Tool inventory
Tools (3)
🟡draft_letter(api_key, to, from_address, html, pdf_path, ...)
Create a letter DRAFT: verifies the recipient address with PostGrid, screens content, and returns a price quote. This NEVER mails anything. Pass EITHER html (letter body as an HTML string) OR pdf_path (path to a PDF file on the server). PDF text is extracted for screening; if extraction fails the draft is kept but flagged needs_review.
Input Schema
{
"type": "object",
"properties": {
"api_key": {
"type": "string",
"description": "your 3L-Group Technology API key (lms_...)."
},
"to": {
"additionalProperties": true,
"type": "object",
"description": "recipient address dict with name, address_line1, address_city,\naddress_state, address_zip (US)."
},
"from_address": {
"additionalProperties": true,
"type": "object",
"description": "sender address dict, same shape as `to`."
},
"html": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"default": null,
"description": "letter body as an HTML string (use this OR pdf_path)."
},
"pdf_path": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"default": null,
"description": "server-local path to a PDF to mail instead of html."
},
"color": {
"default": false,
"type": "boolean",
"description": "True for color printing, False for black & white."
},
"quantity": {
"default": 1,
"type": "integer",
"description": "number of identical letters (10+ gets the bulk rate)."
},
"description": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"default": null,
"description": "optional label for your own records."
},
"certified": {
"default": false,
"type": "boolean",
"description": "OPT-IN ONLY — True for USPS Certified Mail with Electronic\nReceipt (tracked, signature on delivery). Defaults to False, which\nsends standard First Class mail. Only set True when the customer\nexplicitly asked for certified mail: it costs significantly more\n(PostGrid's certified rate + the flat $1.00 service fee, roughly\n$11 per letter). Never default this to True."
}
},
"required": [
"api_key",
"to",
"from_address"
],
"additionalProperties": false
}Output Schema
{
"type": "object",
"additionalProperties": true
}🟡request_send(api_key, draft_id)
Request that a draft be mailed. approval-tier keys: creates a PENDING request and returns a one-tap Allow/Deny approval_url for the human. Nothing is mailed until Allow. on_command keys: may auto-send inside guardrails (spend caps, content screening, anomaly detection); anything outside them stays PENDING.
Input Schema
{
"type": "object",
"properties": {
"api_key": {
"type": "string",
"description": "your 3L-Group Technology API key (lms_...)."
},
"draft_id": {
"type": "integer",
"description": "the draft_id returned by draft_letter."
}
},
"required": [
"api_key",
"draft_id"
],
"additionalProperties": false
}Output Schema
{
"type": "object",
"additionalProperties": true
}🟡send_status(api_key, request_id)
Check a send request: status (PENDING/SENT/REJECTED/FAILED), the key's trust tier and tier decision, approval state (+approval_url while pending), and billing state (Stripe charge id when billed).
Input Schema
{
"type": "object",
"properties": {
"api_key": {
"type": "string",
"description": "your 3L-Group Technology API key (lms_...)."
},
"request_id": {
"type": "integer",
"description": "the request_id returned by request_send."
}
},
"required": [
"api_key",
"request_id"
],
"additionalProperties": false
}Output Schema
{
"type": "object",
"additionalProperties": true
}Community
Evidence