PostAgent

tech.interpretaiPublished by interpretai.techv0.5.0Updated Oct 25, 2026

Print & mail PDF/HTML/Markdown/text/DOCX/images to US addresses; pay per call in x402 USDC on Base.

VerifiedStreamable HTTPWeb executableFinanceBusiness & Commerce

Overview

AI-generated overview

PostAgent lets an assistant upload documents, get a price, pay in USDC on Base and physically mail letters or postcards to US addresses.

What you can do
Upload finished letters or reusable mail-merge templates, and postcard artwork for front or back sides, as PDF, HTML, Markdown, text, DOCX or images, normalized to print-ready PDF where applicable. Verify sender and recipient addresses, including standalone paid address verification with standardized US and international results. Get quotes that lock a 15-minute USDC price for letters, postcards and bulk campaigns of up to 500 recipients. Pay a quote through an x402 wallet, a Stripe shared payment token, or a Stripe-hosted card checkout page handed to a human. Track mail jobs and campaigns, including carrier, tracking, proof data and per-recipient validation counts. Check the live agent-shi-
When to use it
Use it when an assistant needs to send a real physical letter or postcard to a US address, run a mail merge or bulk campaign, or verify an address before mailing. It suits agents with an x402-capable wallet that can pay per send without a human in a browser.
Requirements
A remote streamable HTTP endpoint; no local package. A US sender and US recipient address (2-letter state code, 5-digit or ZIP+4). An x402-capable wallet holding USDC on Base mainnet for per-send payment, or a Stripe shared payment token, or a human with a card for the hosted checkout. Campaigns require the paying wallet to pass KYC.
Before you install
Sending mail spends real money and is irreversible once submitted. Payments are per send in USDC on Base, and address verification also costs a small USDC fee per call. Bulk campaigns are x402-only and require KYC on the paying wallet. The server declares no authentication, so wallet and payment credentials are handled by the agent's own wallet client; review quotes and confirm before paying.

Installation

In SourceWeft

  1. Open PostAgent in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/tech.interpretai%2FPostAgent/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "postagent": {
      "type": "http",
      "url": "https://api.postagent.sh/mcp"
    }
  }
}

README

PostAgent — Print & Mail (Agent Skill)

An installable agent skill that lets your AI coding agent print and physically mail a document (PDF, HTML, Markdown, text, DOCX, or image) to a US postal address via the PostAgent API. Each send is paid per-call in USDC on Base using the x402 payment protocol, then handled by PostAgent's print-and-mail workflow.

Sending mail spends real money and is irreversible once submitted. The skill always quotes first and requires explicit user confirmation before paying.

Install

Claude Code (global) — always pass -a claude-code so it lands in ~/.claude/skills/, the only place Claude Code reads skills from:

bash
npx skills add interpretai-tech/agent-tools --skill postagent-print-and-mail -g -a claude-code -y

Then restart Claude Code — the skill list is read once at session start, so a newly installed skill won't appear until you relaunch.

Other agents (auto-detected — installs to each agent's own skills dir, e.g. .agents/skills/ for Codex/Cursor/Gemini):

bash
npx skills add interpretai-tech/agent-tools --skill postagent-print-and-mail -y

Without -a claude-code, the CLI may install only to the generic .agents/skills/ path, which Claude Code does not read — the skill will appear "installed" but never load.

-y skips the interactive scope/confirmation prompt. Drop it if you prefer to confirm the scope and review before install.

What it does

  1. Upload a document (free) — finished letter or {{field}} mail-merge template.
  2. Quote (free) — verifies sender/recipient addresses and locks an inclusive USDC price for 15 minutes.
  3. Pay — the agent's x402 wallet pays the quote's paymentUrl; PostAgent prints and mails the letter.
  4. Track (free) — poll job status and USPS tracking.

Works in any agent via the REST API (plain HTTP, no setup) — and optionally via the PostAgent MCP server (https://api.postagent.sh/mcp) when it's configured. See SKILL.md for the full instructions the agent follows.

Requirements

  • A US sender and US recipient address (2-letter state code, 5-digit/ZIP+4).
  • An x402-capable wallet with USDC on Base mainnet to pay per send.

License

MIT

Source: postagent-print-and-mail/README.md at commit bd1e71b

Tools

14

check_postagent_updates

Check latest PostAgent skill and MCP versions

Fetches the live PostAgent agent manifest. Call this before using PostAgent in a new session, after reconnecting the MCP server, or when an installed PostAgent skill may be stale. If the installed skill is older than latestSkillVersion, read latestSkillUrl and follow those instructions for this turn; if updateRequired is true, do not perform paid or irreversible PostAgent actions until the user updates.

ParametersinstalledMcpVersioninstalledSkillVersion

create_letter

Upload a finished letter (identical content, no mail merge)

Upload and normalize a FINISHED, ready-to-mail document to PDF. Choose this when the content is final and IDENTICAL for every recipient — including when you mail the same letter to many people (just quote/pay once per recipient with the same documentId). The exact bytes you give are what gets printed. Use create_template instead only when the content must vary per recipient via {{fields}}. Returns a documentId, the stored page count, byte size, and source format. Free; no payment required. Provide the document EXACTLY ONE way: `content` (inline text, for html/markdown/text), `contentBase64` (base64-encoded binary, for pdf/docx/image), or `url` (a publicly reachable URL the server fetches). Supplying none, or more than one, is an error. Maximum upload size is 31457280 bytes (~30 MB); output page size is US Letter. Any `{{...}}` text is printed LITERALLY here — it is NOT treated as a merge field. If you want personalized mail merge across recipients, use `create_template` instead. Reserved address zone: a recipient address block is printed over the top ~3 inches of page 1, so the server reserves that space for you automatically. For text/html/markdown/docx, page-1 content is pushed below the block (content may therefore flow onto an additional page); for pdf and image inputs, a blank first page is prepended. As a result the returned page count — and the selected-provider cost behind the resulting quote — can be higher than your source document (e.g. a single-page PDF is stored as 2 pages). You do NOT need to leave the top of your document blank yourself. See the postagent://formats resource for per-format details.

ParametersurlformatcontentfilenamecontentBase64

create_template

Upload a mail-merge template (content varies per recipient)

Upload a REUSABLE template containing `{{field}}` placeholders (e.g. `Dear {{name}},` or `Balance due: {{amount}}`). Choose this ONLY when the content must vary per recipient (mail merge) — recipient count is irrelevant, so a single personalized letter belongs here too. If the content is identical for everyone, use create_letter instead (this tool rejects input with no `{{fields}}`). Returns a documentId with `kind: "html_template"`, a `mergeFields` list of the detected field names, and an `estimatedPageCount`. Free; no payment required. Template source must be TEXT-BASED (html, markdown, or text) and must contain at least one `{{field}}`, or the upload is rejected — for a finished document with no merge fields, use `create_letter`. Provide the template EXACTLY ONE way: `content` (inline text), `contentBase64` (base64-encoded text), or `url` (a publicly reachable URL the server fetches). Supplying none, or more than one, is an error. Maximum upload size is 31457280 bytes (~30 MB); output page size is US Letter. Reuse one template documentId across recipients: call create_mail_quote ONCE PER RECIPIENT, supplying that recipient's values via `mergeVariables` (every field in `mergeFields` must have a non-empty value). The server substitutes the values and renders that recipient's personalized PDF at quote time, so `estimatedPageCount` is only a baseline — the binding page count and price are set per quote from the actual rendered output. Reserved address zone: a recipient address block is printed over the top ~3 inches of page 1, so the server reserves that space automatically (page-1 content is pushed below the block and may flow onto an additional page). You do NOT need to leave the top blank yourself. See the postagent://formats resource for details.

ParametersurlformatcontentfilenamecontentBase64

create_mail_quote

Get a locked price quote for a print-and-mail job

Verifies the recipient and sender US addresses and locks a 15-minute USDC price for a documentId. Does not charge or mail anything. Returns a `paymentUrl` (a per-quote x402-payable URL); the preferred way to actually mail the letter is for the agent's wallet to perform an in-band x402 payment against that URL (e.g. `npx awal@latest x402 pay <paymentUrl>`). The MCP `submit_paid_mail_job` tool is a fallback for clients that can emit a standalone signature header. In all cases, show the recipient, sender, options, selected-route `design` constraints, price, AND any `fulfillment.warnings` to the user and get explicit confirmation before paying. The response includes a `fulfillment` block with `requested` (what you asked for), `selected` (what will actually be printed/mailed) and `warnings` (any soft-preference downgrades — e.g. `service_level_downgraded` or `extra_service_unavailable`); do not pay through a non-empty warnings list without re-confirming the trade-off with the user. The response also includes a provider-neutral `design` block; inspect it and the preview before paying because the selected delivery method determines print address/no-ink zones.

ParameterstorequiredfromoptionsdocumentIdrequiredmergeVariables

create_card_checkout

Create a hosted credit-card checkout link for a quote

Creates a Stripe-hosted Checkout page for a locked quote and returns a `checkoutUrl` plus a `statusUrl`. Use this as the LAST-RESORT payment rail, when the payer is a human paying by credit card (the agent cannot complete card entry itself). Hand the `checkoutUrl` to the user to open in a browser and pay; payment is asynchronous — once they finish, the letter is created automatically by Stripe's webhook. To track it without a job id, GET the returned `statusUrl` (`/v1/quotes/:quoteId/job`): it returns `found:false` with status `pending`/`processing` until the webhook creates the job, then the full job (id, status, tracking). Prefer x402 (or MPP, if available) for autonomous agent payment. Returns an error if Stripe Checkout is not enabled on the server. No charge occurs until the human completes the hosted page.

ParametersquoteIdrequiredwebhookUrl

pay_mail_with_shared_payment_token

Pay a quote autonomously by card/wallet via a Shared Payment Token (MPP)

Autonomous, no-browser FIAT payment for a locked quote using a Stripe Shared Payment Token (SPT / Machine Payments Protocol). Use this when the agent can mint an SPT on the buyer's behalf and wants to pay by card/wallet without a human in a browser (prefer x402 first if the agent has a USDC-on-Base wallet; this is the autonomous fiat alternative). CHARGES MONEY AND IS IRREVERSIBLE: the server authorizes the SPT, prints the letter, then captures — a job comes back inline (no polling needed). Only call after the user has explicitly confirmed the recipient, sender, content, and price from create_mail_quote. Minting the token (the agent's responsibility, NOT this server): the SPT must be scoped to THIS seller's Stripe profile and to at least the quote amount. The quote's `paymentOptions` entry for `mpp` carries the `stripeProfileId`, `currency`, `maxAmountCents`, and `expiresAt` you need. Mint it with the buyer's payment method via the Stripe `@stripe/link-cli` (`spend-request create … --network-id <stripeProfileId> --credential-type shared_payment_token`) or the SharedPaymentIssuedToken API, then pass the resulting `spt_…` here. SPTs are US-only and cards carry a 0.50 USD minimum. Returns an error if MPP is not enabled/configured on the server.

ParametersquoteIdrequiredwebhookUrluserConfirmedrequiredsharedPaymentTokenrequired

prepare_mail_payment

Fetch the x402 payment challenge for a quote

Returns the x402 PAYMENT-REQUIRED challenge for a locked quote so an x402-capable wallet client can sign it. No payment is taken at this step. Probes the canonical per-quote pay URL (`/v1/quotes/:quoteId/pay`). The preferred way to actually pay is for the wallet to perform the standard x402 in-band handshake against `paymentUrl`; this tool is for inspection or for the detached-signature flow via `submit_paid_mail_job`.

ParametersquoteIdrequired

submit_paid_mail_job

Submit a signed x402 payment to create and mail the letter

Detached-signature fallback for x402 wallets that can emit a standalone PAYMENT-SIGNATURE header. THE PRIMARY/RECOMMENDED PATH is for the agent's wallet to pay the quote's `paymentUrl` in-band (e.g. `npx awal@latest x402 pay <paymentUrl>`); use this tool only if your wallet client cannot do that. Charges the agent in USDC on Base mainnet and creates a physical letter for printing and mailing. THIS IS IRREVERSIBLE. Only call after the user has explicitly confirmed the recipient, sender, content, and price returned by create_mail_quote, and after obtaining the signed x402 payment header (see prepare_mail_payment).

ParametersquoteIdrequiredwebhookUrluserConfirmedrequiredpaymentSignaturerequired

get_mail_job_status

Get the current status of a mail job

Returns normalized status, carrier/tracking/proof data, and tracking events for a previously created job.

ParametersjobIdrequired

create_postcard_art

Upload postcard artwork (front or back)

Upload ONE side of a postcard (front or back) as single-page PDF, PNG, or JPEG artwork. The file is stored VERBATIM — no page-size normalization and no reserved address zone — so you are responsible for the correct trim size plus bleed: 4x6 cards need 4.25"x6.25" artwork, 6x9 needs 6.25"x9.25", 6x11 needs 6.25"x11.25" (0.125" bleed on each edge). The selected delivery method prints the recipient address block over part of the BACK, so keep that area clear of critical content and review the quote's `design` block before payment. Returns a documentId with kind "postcard_art". Upload front and back separately, then quote with create_postcard_quote. Free; no payment required. Provide the artwork EXACTLY ONE way: `contentBase64` (base64-encoded pdf/png/jpeg) or `url` (publicly reachable). Text-based formats are rejected — postcards are artwork, not documents.

ParametersurlformatfilenamecontentBase64

create_postcard_quote

Get a locked price quote for printing and mailing a postcard

Verifies the recipient and sender addresses and locks a 15-minute USDC price for mailing a postcard built from two postcard_art documents (front + back, uploaded via create_postcard_art). Sizes: 4x6 (default), 6x9, 6x11 — postcards always print in full color. US recipients use the strict US address shape; INTERNATIONAL recipients are supported on 4x6 only (set `to.country` to the 2-letter ISO code; the sender must still be a US address). Payment works exactly like letters: pay the returned `paymentUrl` via x402, or use the MPP/checkout fallbacks. Show the recipient, sender, size, selected-route `design` constraints, price, AND any `fulfillment.warnings` to the user and get explicit confirmation before paying — service level is a soft preference and may have been downgraded (e.g. international economy is upgraded to standard) with a `service_level_downgraded` warning the agent must surface verbatim.

ParameterstorequiredfromoptionsbackDocumentIdrequiredfrontDocumentIdrequired

verify_address

Verify a postal address for deliverability (paid, flat fee)

Standalone paid address verification — no mail is sent. Checks whether an address is deliverable and returns the standardized form (US: CASS with ZIP+4; international: per-country matching). Costs a small flat USDC fee per call via x402 (a fraction of a cent vs. mailing). Two-step flow, like the mail rails: call WITHOUT `paymentSignature` to get the 402 challenge and `paymentUrl` (preferred: have the agent's x402 wallet pay `paymentUrl` in-band with the address as the JSON POST body `{"address":{...}}`); or sign the challenge and call again WITH `paymentSignature` to verify and get the result in one round trip. US addresses need line1 + (city+state or zip). International addresses need line1 + country. Note: when mailing through PostAgent you do NOT need this tool — create_mail_quote already verifies sender and recipient for free as part of the quote.

Parameterszipcitynameline1requiredline2statecountrypaymentSignature

create_campaign_quote

Get a locked price quote for a bulk mail campaign (KYC required)

Quote ONE bulk send to MANY recipients (up to 500): a single template or static document, fulfilled through PostAgent's campaign workflow. Price is an inclusive customer-facing total, locked for 15 minutes. Payment is x402 ONLY. IMPORTANT — KYC WALL: campaigns require the paying wallet to be identity-verified with PostAgent. Verification is operator-run, not self-serve: until the wallet is verified this tool returns `kyc_required` (403). Do not retry the same wallet — instead either mail recipients individually with create_mail_quote, or request campaign access at https://interpretai.tech/contact (this URL is also returned in the 403's details.contactUrl) to get the wallet enabled. Usage once the wallet is verified: upload a template with create_template (using {{fields}}) or a finished letter with create_letter, then call this with `recipients` (each `to` a US address, plus per-recipient `mergeVariables` for templates) and the `payerWallet` that will pay the quote. The print partner validates every recipient address after payment; failed recipients are excluded and their share refunded (processed manually). Track via get_campaign_status.

ParametersfromnameoptionsdocumentIdrequiredrecipientsrequiredpayerWalletrequired

get_campaign_status

Get the status of a bulk mail campaign

Returns a campaign's validation/sending progress: status (validating | sent | partial | failed), recipient counts (total / validated / failed), and a failures report URL when some recipients could not be validated. Polling this endpoint also advances the campaign (it releases the campaign for mailing once the print partner finishes validating the audience). Find the campaign id on the quote's job status (GET jobStatusUrl) after payment.

ParameterscampaignIdrequired

Version history

1
  1. v0.5.0LatestSep 16, 2026

Score

90% of the applicable checks met

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  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts

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