postalref

com.postalref/postalrefpostalref.comstreamable-httpv0.1.0Scanned 2 hours ago

USPS package barcodes, service type codes and mailing terms, each cited to its USPS source.

7 tools: 3 change things and 4 only read.

Reads private data · 5
Reads text others write · 0
Can send data out · 1
2 findings

Anlyon alternative

3 of these tools change something. Run those as governed actions.

Declare what an action changes, and Anlyon puts it under a shared limit, binds every approval to the exact request, and grades the outcome. It works on any HTTPS API you can describe as an action.

Anlyon does not run, proxy or govern this MCP server. A tool your own code calls directly is not routed through Anlyon and is not governed by it.

Import an OpenAPI spec →

Tools

Grouped by what each tool does, most consequential first. Open one for its reasons and full description; descriptions are the publisher's own words.

7 tools

Changes things 3Creates or changes something that can be changed back.Claude Code: ask

defineWhat USPS means by a name or abbreviation: each registry entry it names, with the USPS words that define it and the page they're on, its other names, postalref's own explanation wh…No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
What USPS means by a name or abbreviation: each registry entry it names, with the USPS words that define it and the page they're on, its other names, postalref's own explanation where it has one, and postalref's page about it.
Annotations the server declares
- title: Define a USPS term
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
diffWhat changed in a code table or document between two editions: each code added, removed or changed and each changed section, rated editorial, additive or breaking, with who rated i…Reads private dataCan send data out1 finding
Why it is in this group
- The name "diff" says "diff": a word for reading.
- The input takes a statement or command to run (input.code), which can change anything it can reach.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
What it can reach
- private-dataThe description's first sentence says "table": it reads databases.
- outboundThe input takes a destination (input.to): what the tool writes goes there.
Findings
- Warn
  The server marks "diff" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "diff" says "diff": a word for reading.
  What this check looks for
Description, as the server wrote it
What changed in a code table or document between two editions: each code added, removed or changed and each changed section, rated editorial, additive or breaking, with who rated it.
Annotations the server declares
- title: Compare two editions
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
lookupLook up a USPS code: its row as USPS prints it in the newest edition that lists it, the codes its cells name, the editions that list it and its history, each row with its passage i…Reads private data1 finding
Why it is in this group
- The name "lookup" says "lookup": a word for reading.
- The input takes a statement or command to run (input.code), which can change anything it can reach.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
What it can reach
- private-dataThe input names a table (input.table), and the tool reads: it reads databases.
Findings
- Warn
  The server marks "lookup" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "lookup" says "lookup": a word for reading.
  What this check looks for
Description, as the server wrote it
Look up a USPS code: its row as USPS prints it in the newest edition that lists it, the codes its cells name, the editions that list it and its history, each row with its passage id.
Annotations the server declares
- title: Look up a code
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false

Only reads 4Looks things up and changes nothing.Show 4 read-only tools

decodeRead a package barcode or tracking number (IMpb): its layout, each field's digits and meaning, whether the check digit holds, and the service type code's row in the USPS list, each…No findings
Why it is in this group
- The description's first verb is "read": a word for reading.
Description, as the server wrote it
Read a package barcode or tracking number (IMpb): its layout, each field's digits and meaning, whether the check digit holds, and the service type code's row in the USPS list, each with the passage that says so.
Annotations the server declares
- title: Decode a barcode
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
read_sourceRead a revision of a modeled USPS document page by page, as extracted, to quote it: a quote cites the revision's sha256, the PDF page and the words exactly.Reads private dataNo findings
Why it is in this group
- The name "read_source" says "read": a word for reading.
What it can reach
- private-dataThe description's first sentence says "read" and "document": it reads documents.
Description, as the server wrote it
Read a revision of a modeled USPS document page by page, as extracted, to quote it: a quote cites the revision's sha256, the PDF page and the words exactly.
Annotations the server declares
- title: Read a USPS document
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
searchSearch the codes, terms, specs and documents postalref models, exact names and codes first.Reads private dataNo findings
Why it is in this group
- The name "search" says "search": a word for reading.
What it can reach
- private-dataThe description's first sentence says "search" and "document": it reads documents.
Description, as the server wrote it
Search the codes, terms, specs and documents postalref models, exact names and codes first. A query of 20 or more digits comes back as one to decode.
Annotations the server declares
- title: Search codes and terms
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false
search_documentsSearch every document on PostalPro by title and file name, with its page and newest file.Reads private dataNo findings
Why it is in this group
- The name "search_documents" says "search": a word for reading.
What it can reach
- private-dataThe name "search_documents" says "search" and "document": it reads documents.
- private-dataThe description's first sentence says "search" and "document": it reads documents.
Description, as the server wrote it
Search every document on PostalPro by title and file name, with its page and newest file. postalref models a few of them; those carry a slug for read_source.
Annotations the server declares
- title: Search PostalPro documents
- readOnlyHint: true
- destructiveHint: false
- idempotentHint: true
- openWorldHint: false

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.

Exfil surface

Which tools read private data, which read text someone else can write, and which can send data out. One of each is a path a prompt injection can use.

No private-data, untrusted-input, outbound path in this server alone: no tool is tagged untrusted-input.

Reads private data5: Reads files, mail, messages, databases, secrets, calendars or repositories.; diff
lookup
read_source
search
search_documents
Reads text others write0: Brings in text someone else can write: web pages, inbound email, messages, issues and comments.
Can send data out1: Can carry data to people or systems: it sends, posts or publishes, or takes a recipient, channel or URL.; diff

Other servers in the same agent add their own tools to these paths. Audit your whole setup to see them together.

Findings

Matches of fixed checks, with the text they matched.

2 warn

Warnlookup
The server marks "lookup" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "lookup" says "lookup": a word for reading.
What this check looks for
Warndiff
The server marks "diff" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true,"destructiveHint":false,"idempotentHint":true,"openWorldHint":false}; The name "diff" says "diff": a word for reading.
What this check looks for

History

Changes to its tool definitions and to its remote endpoint, newest first.

No change seen yet. Its tools are rescanned every day, and a remote endpoint is looked at once a week.

All changes to this server

Install

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

claude mcp add --transport http postalref https://postalref.com/mcp

claude mcp add --transport http postalref https://postalref.com/mcp

Run in a terminal.

Claude Code permissions

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

.claude/settings.json

{
  "permissions": {
    "allow": [
      "mcp__postalref__decode",
      "mcp__postalref__search",
      "mcp__postalref__read_source",
      "mcp__postalref__search_documents"
    ],
    "ask": [
      "mcp__postalref__lookup",
      "mcp__postalref__diff",
      "mcp__postalref__define"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. A read that can send data out (it takes a URL, say) asks first too. It assumes the server is installed as postalref. Review it before you use it.

Capability tags behind 5 rules

mcp__postalref__lookup private-data
mcp__postalref__diff private-data, outbound
mcp__postalref__search private-data
mcp__postalref__read_source private-data
mcp__postalref__search_documents private-data

Keep the decision: fail CI when the tools change, follow every change, or show a badge.

Pin in CI

Fail a build when the tools you reviewed are not the tools the server serves today.

curl -s "https://anlyon.dev/api/v1/servers/com.postalref/postalref/verify?hash=6284d9c0327a627c7001d7f2770852832b078b3384c3f9ab4ee3a82384f85c9b" | jq -e '.changed == false'

Pinned hash 6284d9c0327a, from Oct 31, 2026, 18:18 UTC.

Watch

Get told when its tools change: a new tool, a new description, a new class.

https://anlyon.dev/servers/com.postalref/postalref/changes.xml

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Badge

[![anlyon.dev](https://anlyon.dev/badge/com.postalref/postalref.svg)](https://anlyon.dev/servers/com.postalref/postalref)

Source: MCP Registry. Synced Oct 31, 2026, 18:17 UTC.