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PaperAgent — Send Physical Mail

by paperagent.dev · remote · no sign-in to list tools · v0.1.0 · published by dev.paperagent

Mail one-off USPS letters from ChatGPT or Claude after you approve the preview and price. US only.

Deletes · 1Final · 2Changes · 11 high finding

8 tools: 1 can delete or cancel things, 2 do something that can't be undone, 1 change things and 4 only read.

Scanned Oct 21, 2026

2 checks matched something in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http letters https://paperagent.dev/mcp

Findings

Matches of fixed checks, with the text they matched.

1 high1 warn
  • The description contains "do not tell the user", an instruction to keep something from the user.

    Matched text

    description: "...ivery date and never reports delivery — do not tell the user a letter arrived unless the status itse..."

    What this check looks for
  • The server marks "preview_draft" as not read-only (readOnlyHint: false), and its words say it reads.

    Matched text

    annotations: {"readOnlyHint":false,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "preview_draft" says "preview": a word for reading.

    What this check looks for

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

8 tools

Deletes or cancels 1Claude Code: deny
  • send_letterCreate an order for a real, physical letter through the United States Postal Service.No findings

    Why it is in this group

    • The name "send_letter" says "send": a word for sending, and what is sent cannot be taken back.
    • The description says "irreversible".
    • The server marks it destructive (destructiveHint: true).
    Description, as the server wrote it
    Create an order for a real, physical letter through the United States Postal Service. It returns a payment link; no paper is printed, postage is bought, or letter is mailed until payment completes. Use this whenever the user asks to mail, post, send by post, or physically send a letter, notice, or document to a street address. This is NOT email — use an email tool for email. US domestic addresses only. Requires a draft_id from create_draft and confirm_total_cents matching the current quote. The letter becomes irreversible once we print it.

    Annotations the server declares

    • title: Send a Physical Letter (USPS)
    • readOnlyHint: false
    • destructiveHint: true
    • idempotentHint: true
    • openWorldHint: true
Can't be undone 2Claude Code: ask
  • create_draftCreate a draft of a physical letter to be printed on paper and mailed through USPS, and return its draft_id, page count and total price.No findings

    Why it is in this group

    • The name "create_draft" says "create": a word for a change.
    • The input addresses people (input.to): what it sends cannot be taken back.
    Description, as the server wrote it
    Create a draft of a physical letter to be printed on paper and mailed through USPS, and return its draft_id, page count and total price. A letter is at most 6 printed pages, at the same price whatever its length: up to 3 pages print one-sided, 4 to 6 print on both sides. Write the body to fit, or split a longer document into two letters, because a body that renders to 7 or more pages is refused rather than trimmed. This is NOT email, fax or text message — nothing reaches the recipient electronically, and the only way this letter arrives is on paper in an envelope. The body is plain text or Markdown. The draft freezes the content and the price for 24 hours and costs nothing; no paper is printed and no postage is bought until send_letter is called. US domestic addresses only. Call preview_draft next so the user can see the letter and the total.

    Annotations the server declares

    • title: Create a Letter Draft
    • readOnlyHint: false
    • destructiveHint: false
    • idempotentHint: false
    • openWorldHint: false
  • update_draftChange the recipient, body, tier or colour of a draft that has not been sent, and re-price it.No findings

    Why it is in this group

    • The name "update_draft" says "update": a word for a change.
    • The input addresses people (input.to): what it sends cannot be taken back.
    Description, as the server wrote it
    Change the recipient, body, tier or colour of a draft that has not been sent, and re-price it. Returns a new page count and a new quote, so the previous total is void — state the new total to the user before sending. The 6-printed-page maximum applies to the new body as well: a replacement that renders to 7 or more pages is refused and the draft is left as it was. This creates nothing and mails nothing.

    Annotations the server declares

    • title: Update a Letter Draft
    • readOnlyHint: false
    • destructiveHint: false
    • idempotentHint: false
    • openWorldHint: false
Changes things 1Claude Code: ask
  • preview_draftReturn a link to the rendered PDF of a draft together with its page count and current total price.1 finding

    Why it is in this group

    • The name "preview_draft" says "preview": a word for reading.
    • The server marks it as not read-only (readOnlyHint: false).

    Findings

    • Warn

      The server marks "preview_draft" as not read-only (readOnlyHint: false), and its words say it reads.

      Matched text

      annotations: {"readOnlyHint":false,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "preview_draft" says "preview": a word for reading.

      What this check looks for
    Description, as the server wrote it
    Return a link to the rendered PDF of a draft together with its page count and current total price. Refreshes the stored price quote when pricing has changed. Use this to show the user exactly what will be printed and exactly what it costs before calling send_letter. The total in the response is the number send_letter requires as confirm_total_cents. This does not create an order or mail a letter.

    Annotations the server declares

    • title: Preview a Letter Draft
    • readOnlyHint: false
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false
Only reads 4Claude Code: allow
  • get_letter_statusReturn the current state of one letter: where it is, the date it goes to USPS, and the estimated delivery date.1 finding

    Why it is in this group

    • The name "get_letter_status" says "get": a word for reading.

    Findings

    • High

      The description contains "do not tell the user", an instruction to keep something from the user.

      Matched text

      description: "...ivery date and never reports delivery — do not tell the user a letter arrived unless the status itse..."

      What this check looks for
    Description, as the server wrote it
    Return the current state of one letter: where it is, the date it goes to USPS, and the estimated delivery date. USPS does not scan plain First-Class letters at delivery, so a Standard letter ends at an expected delivery date and never reports delivery — do not tell the user a letter arrived unless the status itself says so. This creates nothing and mails nothing.

    Annotations the server declares

    • title: Get Letter Status
    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false
  • get_pricingReturn the published price list for mailing physical letters through USPS: the products on sale, what each one costs, how many pages it covers, and when sales tax applies.No findings

    Why it is in this group

    • The name "get_pricing" says "get": a word for reading.
    Description, as the server wrote it
    Return the published price list for mailing physical letters through USPS: the products on sale, what each one costs, how many pages it covers, and when sales tax applies. Amounts are in US cents. Every letter is one of these prices — there is no volume discount, no per-page charge and no colour printing — so quote the tier total and say New York sales tax is added, whatever the destination. Call this before telling a user what a letter will cost. This creates nothing and mails nothing.

    Annotations the server declares

    • title: Get Letter Pricing
    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false
  • list_lettersReturn this account's letters, newest first, with the status, mail date and total for each.No findings

    Why it is in this group

    • The name "list_letters" says "list": a word for reading.
    Description, as the server wrote it
    Return this account's letters, newest first, with the status, mail date and total for each. Use this to answer questions about what has already been sent. This creates nothing, changes nothing and mails nothing.

    Annotations the server declares

    • title: List Letters
    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false
  • validate_addressCheck a US postal address and return it in the normalized form the envelope will be printed with, plus any warnings.No findings

    Why it is in this group

    • The name "validate_address" says "validate": a word for reading.
    Description, as the server wrote it
    Check a US postal address and return it in the normalized form the envelope will be printed with, plus any warnings. The address is checked against the Google Address Validation service, which receives the address and nothing else. Use this before create_draft whenever the address came from a person rather than from an earlier tool result. Requires a complete street address: this does not look up, append or find an address from a name, and it does not handle addresses outside the United States. This creates nothing and mails nothing.

    Annotations the server declares

    • title: Validate a US Postal Address
    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: true

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 0.1.0. Values in angle brackets are yours to fill in.

claude mcp add --transport http letters https://paperagent.dev/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json
{
  "permissions": {
    "allow": [
      "mcp__letters__get_pricing",
      "mcp__letters__validate_address",
      "mcp__letters__get_letter_status",
      "mcp__letters__list_letters"
    ],
    "ask": [
      "mcp__letters__create_draft",
      "mcp__letters__update_draft",
      "mcp__letters__preview_draft"
    ],
    "deny": [
      "mcp__letters__send_letter"
    ]
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as letters. Review it before you use it.