# postalref (remote · postalref.com)

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

- Trust score: 66/100 (medium)
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-11-05

## Components

- remote · `postalref.com`: 66/100 (this document), [markdown](https://verifymcp.io/servers/com-postalref-postalref/postalref.md), [page](https://verifymcp.io/servers/com-postalref-postalref/postalref)

## Channel facts

- Endpoint: `https://postalref.com/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `0.2.0`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-11-05.

- **Endpoint Security**: 63/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one.
  - HTTPS enforcement could not be verified: the plaintext port answered with HTTP 405, which proves neither a plaintext path nor enforcement.
  - HSTS check failed: the Strict-Transport-Security header is absent.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 61/100
  - AI-judged instruction clarity (good).
  - Context-footprint check failed: tool/resource definitions use about 1498 tokens (~187/item across 8 items; 8 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 17/100
  - Stability observed for 5 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 99/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 96% of tool parameters carry a description.
  - Structured output schemas are declared (100% of tools); any adoption earns full credit.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 8 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 9 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.

## Install

### How do I install the postalref MCP server?

postalref is a hosted endpoint at https://postalref.com/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

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

### Cursor

```json
{
  "mcpServers": {
    "com-postalref-postalref": {
      "url": "https://postalref.com/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "com-postalref-postalref": {
      "type": "http",
      "url": "https://postalref.com/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.com-postalref-postalref]
url = "https://postalref.com/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "com-postalref-postalref": {
      "type": "remote",
      "url": "https://postalref.com/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add com-postalref-postalref --url 'https://postalref.com/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  com-postalref-postalref:
    url: "https://postalref.com/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "com-postalref-postalref": {
      "Transport": "http",
      "Url": "https://postalref.com/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add com-postalref-postalref -t streamable-http -u 'https://postalref.com/mcp'
```

### Other

```json
{
  "mcpServers": {
    "com-postalref-postalref": {
      "type": "http",
      "url": "https://postalref.com/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-11-05 (score 66, 0)

- [security] The server rewrote its instructions, which are the text every model session reads
- [security] Tool “read_source” rewrote its description, which is the text the model reads
- [security] Tool “search_documents” rewrote its description, which is the text the model reads
- [functional regression] Schema quality: 157 → 187
- [functional] New tool “search_text”
- [cosmetic] “lookup” reworded the description of “table”
- [cosmetic] “read_source” reworded the description of “document”
- [cosmetic] “read_source” reworded the description of “page”

### 2026-11-03 (score 66, 0)

- [security] Tool “define” rewrote its description, which is the text the model reads

### 2026-11-02 (score 66, +1)

No change was recorded against any check on this day. Stability & Change Management went from 3 to 7. That category is still filling its 30-day observation window: 1 days of observed history at the previous scan, 2 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-11-01 (score 65, 0)

- [security] Tool “define” rewrote its description, which is the text the model reads
- [security] Tool “lookup” rewrote its description, which is the text the model reads
- [security] Tool “search” rewrote its description, which is the text the model reads
- [functional regression] Schema quality: 127 → 153
- [functional improvement] Stability: unverified → 0.03
- [functional] Server version: 0.1.0 → 0.2.0

### 2026-10-31 (score 65)

First indexed and scored.

## MCP tools (8)

### `decode` (~61 tokens)

Decode a barcode

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.

Input parameters:

- `barcode` (string, required)

Output parameters:

- `checks` (array)
- `digits` (string)
- `fields` (array)
- `format` (object)
- `spec` (object)
- `tracking` (string)
- `verdict` (string)

### `lookup` (~278 tokens)

Look up a code

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. A code is found without the marks USPS prints around it and in a row USPS prints for several codes: 750 finds *750, 858 finds 858 and the dropped 858**, and 13 finds PTR's row 01 / 13. Two digits are also tried as three: 55 finds PTR's 55, then STC's 055.

Input parameters:

- `code` (string, required): A code as USPS prints it: 055, 920, PM, 01.
- `table` (string): One table to look in: stc, extra-services, mail-classes, channel-application-ids, container-types, delivery-option-indicators, rate-indicators, destination-rate-indicators, discount-types, open-and-d…

Output parameters:

- `matches` (array)

### `diff` (~155 tokens)

Compare two editions

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.

Input parameters:

- `code` (string): One code of the table.
- `from` (string): The older edition's date. The edition before `to` when absent.
- `limit` (integer): At most this many changes; 50 when absent.
- `severity` (string): Only changes rated this.
- `subject` (string, required): A code table, such as stc, ptr or extra-services, or a document, such as pub-199 or impb-spec.
- `to` (string): The newer edition's date. The newest when absent.

Output parameters:

- `changes` (array)
- `counts` (object)
- `editions` (array)
- `from` (string)
- `subject` (object)
- `to` (string)
- `total` (integer)

### `search` (~184 tokens)

Search codes and terms

Search the codes, terms, banner texts, specs and documents postalref models, by one index: names and codes whose key is the query's first, then those that start with it, then those with words that start with its words, then codes whose row has its words. A term hit carries its kind (mail-class, extra-service, service, program, system, file, identifier, document, facility, container, role or term) and its tier (core, or reference: only in Publication 32, the glossary of July 2013, with that date). A query of 20 or more digits comes back as one to decode.

Input parameters:

- `limit` (integer): At most this many hits; 10 when absent.
- `query` (string, required): A code, a term or words from a code's row: 055, mailer id, ground advantage.

Output parameters:

- `decode` (string)
- `hits` (array)
- `query` (string)
- `total` (integer)

### `define` (~143 tokens)

Define a USPS term

What USPS means by a name or abbreviation: each registry entry it names, in the order search ranks them, with its kind and tier, 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. An entry USPS ended says when, what replaced it, and USPS's words that say so; one renamed gives its former names, each with USPS's words.

Input parameters:

- `limit` (integer): At most this many entries; 5 when absent.
- `name` (string, required): A name or abbreviation USPS uses: mailer id, MID, CRID, banner text.

Output parameters:

- `entries` (array)
- `match` (string)
- `query` (string)
- `total` (integer)

### `read_source` (~277 tokens)

Read a USPS document

Read any document postalref holds page by page, as extracted, to quote it: a quote cites the revision's sha256, the PDF page and the words exactly. A text without pages, a web page or a product page, reads in parts, and a quote from one cites no page.

Input parameters:

- `document` (string, required): A document's id, as search_documents gives it: a modeled one, such as pub-199 or impb-spec; node-4649 for another PostalPro file; postalpro-855 for a PostalPro product page; or a download such as pdf…
- `find` (string): Words to find, as one phrase, or when no page has the phrase, each word anywhere on a page. Without `page`, the text read is the first pages that have them.
- `page` (integer): The first PDF page, sheet or part to read, counting from 1. Absent with `find`: the pages that have the words.
- `pages` (integer): How many to read, up to 5; 1 when absent.
- `revision` (string): A revision's sha256, or its slug, such as 2026-07-02. The newest when absent.

Output parameters:

- `document` (object)
- `found` (array)
- `match` (string)
- `next` (integer)
- `parts` (integer)
- `revision`
- `revisions` (array)
- `text` (array)

### `search_documents` (~103 tokens)

Search PostalPro documents

Search every document on PostalPro by title and file name, with its page and newest file, and the product pages and downloads postalref holds by title. Each one postalref holds the text of carries the id read_source reads it by.

Input parameters:

- `limit` (integer): At most this many; 10 when absent.
- `query` (string, required): Words from a document's title or file name.
- `topic` (string): Only documents a model put under this topic.

Output parameters:

- `documents` (array)
- `query` (string)
- `total` (integer)

### `search_text` (~200 tokens)

Search the text of documents

Search the text of every document postalref holds for the pages that say the words, best first: those that say them as a phrase, then by how much of the page they are and how many of them it says side by side or close together, a table of contents last, and at most three pages a document. A page needn't have the words a question asks with, such as how, get or take. Each hit gives the id and page read_source reads, and the words around them. Use it when no title names what you're looking for, as for a price in the Mail Classification Schedule or a rule in a DMM chapter.

Input parameters:

- `limit` (integer): At most this many pages; 10 when absent.
- `query` (string, required): Words a page says: a price, a rule, a size, a name. Each word is found in its forms: one or many, -ed, -ing, -able.

Output parameters:

- `hits` (array)
- `match` (string)
- `query` (string)
- `total` (integer)

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/com-postalref-postalref/postalref#diagnostics

## Score history

- 2026-11-05: 66
- 2026-11-04: 66
- 2026-11-03: 66
- 2026-11-02: 66
- 2026-11-01: 65
- 2026-10-31: 65

## Common questions

### What is the postalref MCP server?

postalref is an MCP server listed in the public MCP registry as com.postalref/postalref. USPS package barcodes, service type codes and mailing terms, each cited to its USPS source. This page covers its hosted endpoint (https://postalref.com/mcp).

### Is the postalref MCP server safe to use?

postalref scores 66 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the postalref MCP server expose?

postalref exposes 8 tools: decode, lookup, diff, search, define, and 3 more. Their descriptions and schemas cost roughly 1,401 tokens of context every time the server is loaded.

### Does the postalref MCP server require authentication?

No. We connected to postalref without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the postalref MCP server still maintained?

postalref is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

## Links

- Remote endpoint: https://postalref.com/mcp
- Website: https://postalref.com/
- Changelog RSS feed: https://verifymcp.io/servers/com-postalref-postalref/postalref.xml
- Changelog JSON feed: https://verifymcp.io/servers/com-postalref-postalref/postalref.json
- HTML version of this page: https://verifymcp.io/servers/com-postalref-postalref/postalref