reference-data-mcp-server

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  <h1>@cyanheads/reference-data-mcp-server</h1>
  <p><b>Look up countries, timezones, periodic table elements, physical constants, units, HTTP status codes, and MIME types via MCP. STDIO or Streamable HTTP.</b>
  <div>10 Tools • 3 Resources</div>
  </p>
</div>

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**Public Hosted Server:** [https://reference-data.caseyjhand.com/mcp](https://reference-data.caseyjhand.com/mcp)

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---

## Tools

Ten tools grouped by domain — geo, timezone, periodic table, physical constants, unit conversion, HTTP, and web:

| Tool | Description |
|:---|:---|
| `ref_geo_lookup` | Look up a country by name, ISO alpha-2, or alpha-3 code. Returns capital, region, languages, currencies, calling codes, TLD, flag, and IANA timezone IDs. |
| `ref_geo_search` | Search and filter countries by region, subregion, language, currency, or free-text keyword. |
| `ref_timezone_lookup` | Get timezone info by IANA ID, country code, or partial city/region name. Returns current and standard UTC offsets, DST status, and major cities. |
| `ref_timezone_convert` | Convert a local datetime from one timezone to another, with visible UTC offsets for both sides. |
| `ref_element_lookup` | Look up a periodic table element by name, symbol, or atomic number. Full property set including atomic mass, electron configuration, electronegativity, density, melting/boiling points, and discovery data. |
| `ref_element_search` | Filter elements by category, group, period, atomic number range, or atomic mass range. |
| `ref_constant_lookup` | Look up a CODATA 2022 physical constant by name, symbol, or alias. Returns value, SI unit, uncertainty, and related constants. |
| `ref_unit_convert` | Convert a numeric value between compatible units of measure (length, mass, volume, temperature, speed, pressure, energy, power, frequency, digital storage, angle). |
| `ref_http_status` | Look up an HTTP status code by number or keyword. Returns reason phrase, description, category, cacheability, and RFC reference. |
| `ref_mime_type` | Look up a MIME type by type string or file extension. Returns canonical type, extensions, compressibility, and data source. |

### `ref_geo_lookup`

Look up a country by name, ISO alpha-2 or alpha-3 code.

- Accepts fuzzy name matching — "Brasil" and "Brazil" both resolve
- Returns full record: capital, region, subregion, official languages, currencies, calling codes, TLD, flag emoji, and IANA timezone IDs
- Lookup modes: `auto` (tries alpha-2, alpha-3, then name), `name`, `alpha2`, `alpha3`

---

### `ref_geo_search`

Search and filter countries with at least one filter required.

- Filters: keyword (name, native name, capital, subregion), region, subregion, language (ISO 639-1 code or name), currency (ISO 4217 code or name)
- Returns ranked summaries (alpha-2/3, name, capital, region, primary currency, flag)
- Paginated with configurable limit (1–100); `truncated` flag when results are cut off

---

### `ref_timezone_lookup`

Get timezone info for an IANA ID, country code, or city name.

- Partial city matching: "Tokyo" resolves to "Asia/Tokyo", "NY" to "America/New_York"
- Country code queries return all timezones observed in that country
- Optional `at` parameter evaluates DST state at a specific ISO 8601 moment
- Returns current offset, standard offset, DST status, abbreviations, major cities, and country codes

---

### `ref_timezone_convert`

Convert a local datetime between timezones.

- Input is a local ISO 8601 datetime without offset (e.g., `"2026-05-24T15:30:00"`)
- Accepts full IANA IDs or unambiguous city names
- Handles DST transitions with a two-pass offset refinement
- Returns source and target local datetimes with their respective UTC offsets, plus the UTC equivalent

---

### `ref_element_lookup`

Look up any of the 118 periodic table elements.

- Accepts name, symbol, or atomic number
- Full property set: atomic mass (with estimated flag), electron configuration, group, period, block, category, Pauling electronegativity, density, melting and boiling points in kelvin, phase at STP, radioactivity, natural occurrence, and discovery data
- Data sourced from PubChem/IUPAC 2024; synthetic/unstable elements return `null` for experimentally inaccessible properties

---

### `ref_element_search`

Filter elements across the full periodic table.

- Filters: category (partial match), group (1–18), period (1–7), atomic number range, atomic mass range
- At least one filter required; returns summaries with atomic number, symbol, name, mass, and category

---

### `ref_constant_lookup`

Look up CODATA 2022 physical constants (~360 entries).

- Fuzzy alias matching: "speed of light", "c", "Avogadro's number", "N_A", "Planck", "h", "Boltzmann", "k_B" all resolve
- Returns value, SI unit expression, absolute and relative uncertainty, exact-definition flag, CODATA identifier, and up to 3 related constants

---

### `ref_unit_convert`

Convert between units in 11 measurement domains.

- **Supported:** length (mm–mi), mass (mcg–t), volume (ml–m³), temperature (C/F/K/R, non-linear), speed (m/s, km/h, knot, ft/s), pressure (Pa–psi), energy (J–MWh), power (W–GW), frequency (Hz–GHz), digital storage (b–TB), angle (deg/rad/grad)
- Incompatible unit pairs return a structured error identifying the quantity mismatch
- Temperatures below absolute zero return a specific error with the Kelvin equivalent

---

### `ref_http_status`

Look up HTTP status codes by number or keyword.

- Numeric queries (e.g., `"404"`) return an exact match
- Keyword queries (e.g., `"not found"`, `"too many requests"`) return the closest match plus alternatives
- Returns: reason phrase, description, category (1xx–5xx), cacheability per RFC 9110, defining RFC with section reference

---

### `ref_mime_type`

Look up MIME types by type string or file extension.

- Accepts `"image/webp"`, `".webp"`, or `"webp"` interchangeably
- Extension lookups return the canonical MIME type first; additional types sharing the extension are listed as alternatives
- Returns: extensions, compressibility flag (relevant for Content-Encoding decisions), and data source (iana/apache/nginx)

---

## Resources

| Type | Name | Description |
|:---|:---|:---|
| Resource | `ref://countries/{alpha2}` | Full country record by ISO alpha-2 code (e.g., `ref://countries/DE`). |
| Resource | `ref://elements/{number}` | Full element record by atomic number (e.g., `ref://elements/6` for Carbon). |
| Resource | `ref://timezones/{iana_id}` | Timezone info by IANA ID with slashes URL-encoded as `%2F` (e.g., `ref://timezones/America%2FNew_York`). |

All resource data is also reachable via tools. Use `ref_geo_lookup`, `ref_element_lookup`, and `ref_timezone_lookup` when you need flexible query modes or country search.

---

## Features

Built on [`@cyanheads/mcp-ts-core`](https://www.npmjs.com/package/@cyanheads/mcp-ts-core):

- Declarative tool, resource, and prompt definitions — single file per primitive, framework handles registration and validation
- Unified error handling — handlers throw, framework catches, classifies, and formats
- Pluggable auth: `none`, `jwt`, `oauth`
- Swappable storage backends: `in-memory`, `filesystem`, `Supabase`, `Cloudflare KV/R2/D1`
- Structured logging with optional OpenTelemetry tracing
- STDIO and Streamable HTTP transports

Reference-data-specific:

- Entirely in-memory — all datasets load at startup; no runtime network calls, no API keys, no rate limits
- Works offline and in air-gapped environments
- Seven specialized services: geo (countries-list), timezone (Node.js Intl + @vvo/tzdb), elements (PubChem/IUPAC 2024, 118 elements), constants (CODATA 2022, ~360 entries), units (convert-units), HTTP status (IANA registry), MIME types (mime-db, ~1,000 types)

Agent-friendly output:

- Structured error contracts on every tool — typed `reason` codes (`no_match`, `no_filters`, `unknown_unit`, `incompatible_units`, `below_absolute_zero`, `invalid_timezone`, `invalid_datetime`