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postalref MCP server

Which MCP servers are postalref's own, from the official registry and from asking its own domain, whether they answer, and what they offer. A program checked each of these, nobody copied them from a product page.

read 2026-10-31

← Back to postalref

Whose server it is
  • Registry namecom.postalref/postalrefverified in the MCP registry

The registry name sits under postalref.com. The registry only lets a publisher use that namespace after proving control of the domain through DNS or HTTP.

When we asked itchecked 2026-10-31
  • Stateanswerschecked 2026-10-31
  • Tools7
  • Server calls itselfpostalref
  • Server version0.1.0
  • Protocol version2025-06-18

On 2026-10-31 the server answered initialize and tools/list without a sign-in. First answer in 220 ms.

Should an agent connect itNot proven either way yet
  • Its tools do every use case we checked: look up what a USPS service type code means; decode the service type code in a tracking number; see which codes changed in a USPS revision.
  • Checked on 4 of the 7 days it takes to judge reliability.

Once connected

  • For "look up what a USPS service type code means", the likely first call is lookup.
  • For "decode the service type code in a tracking number", the likely first call is decode.
  • For "see which codes changed in a USPS revision", the likely first call is diff.

Said by rules from the measurements above. The likely first call is a model's pick from the tool list; read its description before relying on it.

Measured dailydaily checks: 4, the first on 2026-10-31
  • INITE MCP scoreafter a weeka score needs 7 daily checks: 4 so far
  • What an agent can do with it3 of 3 use cases
  • Answeredmeasuring4 of the 7 daily checks it takes to print a share
  • Median first answer1216 ms
  • Space in an agent's context≈ 1,428 tokensthe definitions of all its tools (7), which an agent carries on every turn
  • Tool definitionsA · 98 of 100
  • Typed results7 of 7 toolsdeclared outputSchema: results come typed, read once
  • Parameters without a description: in 1 of 7

What an agent can do with it

  • can do · look up what a USPS service type code means
  • can do · decode the service type code in a tracking number
  • can do · see which codes changed in a USPS revision

Each of the product's use cases, put to Jev against this server's tool list: can an agent do it with these tools?

Worth a look

None of the five warning signs in these definitions.

A program checks the server once a day: initialize and tools/list, no model. Tokens are the definitions' length at about four characters a token. The grade averages six checks of every tool's name, description, schema and annotations; it says how well the tools are described, not whether they work. The score weighs what was measured and nothing else: answering (25%), doing the product's job (25%), definitions (20%), context (10%), use (10%) and how readily a client connects (10%). A part that was not measured is left out, and a hidden instruction caps the score at 40. The state of vendors' MCP servers: method and numbers →

Tools it offers7 tools · read 2026-10-31
  • decode

    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.

  • lookup

    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.

  • diff

    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.

  • search

    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.

  • define

    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.

  • read_source

    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.

  • search_documents

    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.

How to connect

Add the server to your MCP client config. Claude Desktop, Cursor and most other clients read this shape:

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

Add it

Claude Code, in a terminal

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

Add to CursorAdd to VS Code

claude.ai, ChatGPT and other clients: add https://postalref.com/mcp as a custom connector in the settings.

Each line is something a program found when it went looking: the registry entry, the server's own answer, a spec that parses. A missing line means we did not find it, not that it does not exist.