Koskamo

Postage Stamp Price MCP

An MCP server that retrieves current USPS postage prices from Notice 123, allowing agents to calculate letter postage by weight, check flat rate prices, and determine stamp requirements for domestic and international mail without requiring API keys.

Endpoint and access

No sign-in to connect and list tools. Individual tools may still need a vendor account, credentials, or permissions; check the documented prerequisites.

Postage Stamp Price MCP logo, by theluckystrikeCommunity listingStreamable HTTPNo sign-inEndpoint checked 2026-11-06Published by theluckystrike
MCP endpoint (Streamable HTTP)
https://postage-stamp-price-mcp.lipmichal.workers.dev/mcp
Vendor documentation

What its tools do

3 tools, grouped by the hints the server advertises. Hints are self-declared, not verified behavior.

Read-only (3)

3 of 3 have a description · 3 of 3 declare behavior hints · 1 of 1 with parameters document them all

Checks and signals

Each line is separate evidence, not a trust score.

  • Passed Endpoint answered the live check ·
  • Availability 1 of 1 checks passed in 30 days

What you can do with it

  • Check current USPS Forever stamp price
  • Calculate postage for letters by weight
  • Get flat rate envelope and box prices
  • Determine international mailing costs

Source and maintenance

Community listingRegistry 1.0.0
mcp-registry: io.github.theluckystrike/postage-stamp-price-mcp@1.0.0Source repository
Maintenance checked

Protocol and capabilities

Server
postage-stamp-price-mcp 1.0.0
MCP protocol negotiated in check
2025-11-25
Tools
3 advertised
Resources
Not advertised
Resource templates
Not advertised
Prompts
Not advertised
Server-advertised capabilities
{
  "tools": {
    "listChanged": true
  }
}

Server-provided instructions

Untrusted server output shown for inspection. It is not Koskamo guidance and is excluded from knowledge search.

Current USPS retail postage prices read at call time from USPS Notice 123, the official price list on pe.usps.com. A model's remembered stamp price is often out of date because USPS changes prices once or twice a year. Use get_stamp_price for "how much is a stamp" and give the effective date.

Tools

3 advertised

get_stamp_price — Get stamp price
Advertised by the server during the last successful anonymous check.
Advertised read-onlyOpen-world

The current USPS Forever stamp price (First-Class Mail 1 oz stamped letter), the 2, 3 and 3.5 oz prices, metered letter prices, postcard, 1 oz large envelope, the nonmachinable surcharge and the 1 oz international letter (Global Forever) price, read at call time from USPS Notice 123 with its effective date.

get_stamp_price input schema
{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "properties": {}
}
get_stamp_price annotations
{
  "title": "How much is a stamp",
  "readOnlyHint": true,
  "openWorldHint": true,
  "idempotentHint": true,
  "destructiveHint": false
}
calculate_letter_postage — Calculate letter postage
Advertised by the server during the last successful anonymous check.
Advertised read-onlyOpen-world

Retail postage for one letter, postcard or large envelope (flat) by weight, to the US, Canada, Mexico or any other country, with the nonmachinable surcharge for square or rigid cards, the total for a quantity, and the number of Forever stamps per piece. Letters up to 3.5 oz, US large envelopes up to 13 oz.

calculate_letter_postage input schema
{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "properties": {
    "type": {
      "enum": [
        "letter",
        "postcard",
        "large_envelope"
      ],
      "type": "string",
      "description": "Default \"letter\"."
    },
    "quantity": {
      "type": "integer",
      "maximum": 10000,
      "minimum": 1,
      "description": "Number of identical pieces, for example 40 holiday cards. Default 1."
    },
    "weight_oz": {
      "type": "number",
      "maximum": 16,
      "description": "Weight in ounces. Default 1.",
      "exclusiveMinimum": 0
    },
    "destination": {
      "type": "string",
      "maxLength": 60,
      "description": "\"US\" (default), \"Canada\", \"Mexico\" or another country name."
    },
    "nonmachinable": {
      "type": "boolean",
      "description": "True for square, rigid, lumpy or vertical letters and cards (adds the surcharge)."
    }
  },
  "additionalProperties": false
}
calculate_letter_postage annotations
{
  "title": "Letter postage",
  "readOnlyHint": true,
  "openWorldHint": true,
  "idempotentHint": true,
  "destructiveHint": false
}
get_flat_rate_prices — Get flat rate box prices
Advertised by the server during the last successful anonymous check.
Advertised read-onlyOpen-world

Current USPS retail prices for Priority Mail Flat Rate envelopes and Small, Medium, Large and APO/FPO/DPO Flat Rate Boxes, and Priority Mail Express Flat Rate envelopes, from Notice 123.

get_flat_rate_prices input schema
{
  "type": "object",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "properties": {}
}
get_flat_rate_prices annotations
{
  "title": "Flat rate prices",
  "readOnlyHint": true,
  "openWorldHint": true,
  "idempotentHint": true,
  "destructiveHint": false
}

Prompts

Not advertised

No prompt definitions available.

Resources

Not advertised

No resource definitions available.

90-day uptime

A lightweight connection check about every six hours, sampled on hosts with many listings. It shows the server answered, not that its tools work.

Too few checks for a percentage yet (1 of 1 answered).

  1. 2026-11-07: 1 of 1 checks answered

30-day availability

Aggregated from read-only remote checks; this is not a tool-execution or security guarantee.

Successful checks
1 of 1 (100%)
Average latency
521 ms
95th percentile latency
521 ms

Maintenance history

Public check and source-refresh events. Editorial and ownership records remain private.

  • · probe · passed · 521 ms · metadata changed · 3 tool(s)

Connect from your client

Each snippet registers the same endpoint; pick the client you use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Claude Code

Run this once in a terminal. It registers the remote server. Use --scope project to write .mcp.json for the repo.
Claude Code configuration
claude mcp add --transport http postage-stamp-price-mcp https://postage-stamp-price-mcp.lipmichal.workers.dev/mcp

Codex

Run this once. Codex stores MCP servers in ~/.codex/config.toml (or .codex/config.toml in a trusted project).
Codex configuration
codex mcp add postage-stamp-price-mcp --url https://postage-stamp-price-mcp.lipmichal.workers.dev/mcp

Cursor

Merge this server into .cursor/mcp.json in your project, then enable postage-stamp-price-mcp in your MCP settings.
Cursor configuration
{
  "mcpServers": {
    "postage-stamp-price-mcp": {
      "url": "https://postage-stamp-price-mcp.lipmichal.workers.dev/mcp"
    }
  }
}

Cline

Merge this into cline_mcp_settings.json (Cline → MCP Servers → Configure).
Cline configuration
{
  "mcpServers": {
    "postage-stamp-price-mcp": {
      "type": "streamableHttp",
      "url": "https://postage-stamp-price-mcp.lipmichal.workers.dev/mcp",
      "disabled": false
    }
  }
}

VS Code

Merge this server into .vscode/mcp.json. Use MCP: List Servers to start postage-stamp-price-mcp and inspect its tools.
VS Code configuration
{
  "servers": {
    "postage-stamp-price-mcp": {
      "type": "http",
      "url": "https://postage-stamp-price-mcp.lipmichal.workers.dev/mcp"
    }
  }
}

Gemini CLI

Run this once. It writes .gemini/settings.json in the current project; pass --scope user for ~/.gemini/settings.json.
Gemini CLI configuration
gemini mcp add --transport http postage-stamp-price-mcp https://postage-stamp-price-mcp.lipmichal.workers.dev/mcp

Claude Desktop

Open Claude Settings > Connectors > Add custom connector, enter this server URL and enable it for the conversation. This is a manual remote-connector handoff, not a desktop JSON configuration.
Claude Desktop configuration
https://postage-stamp-price-mcp.lipmichal.workers.dev/mcp

Windsurf

Merge this into ~/.codeium/windsurf/mcp_config.json, then refresh MCP in Cascade. Windsurf remote servers use serverUrl, not url.
Windsurf configuration
{
  "mcpServers": {
    "postage-stamp-price-mcp": {
      "serverUrl": "https://postage-stamp-price-mcp.lipmichal.workers.dev/mcp"
    }
  }
}

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