eldertongue — Old English dictionary MCP server

A remote Model Context Protocol server that gives LLM agents and editors read-only access to eldertongue.com, an Old English (Anglo-Saxon) dictionary built from Wiktionary data.

The dictionary covers roughly 14,000 headword pages, plus reverse Modern English → Old English lookup and a full Bēowulf verse index. This repository holds the public-facing documentation, client configuration samples, and an agent skill for the hosted MCP endpoint. The server itself is a hosted, managed service — there is no code to run here.

Who it's for

• Agents and assistants that need to look up, inflect, or disambiguate Old English words and want citations back to a stable page URL.

• Editors and IDEs (Claude Desktop, Claude Code, Cursor, VS Code) that speak MCP and want a ready-made reference tool for historical linguistics.

• Developers who prefer plain REST over MCP — every tool has a same-origin REST equivalent (see the table below).

If you only need to read a definition by hand, the website itself is the fastest route. This endpoint exists so a program can get structured, citable data.

Related MCP server: Yomitan MCP Server

Project

Packaging

This repository is also a portable Agent Plugins package: plugin.json holds the manifest, mcp.json declares the hosted Streamable HTTP server, and skills/old-english-lookup/ contains the agent skill. Clients that implement the format can load the MCP server and the skill straight from the repository URL.

server.json is the Official MCP Registry manifest for the hosted endpoint; it is published as io.github.gowinder/eldertongue (version 1.0.0, streamable-http).

Endpoints

All REST paths are rooted at https://eldertongue.com.

Tools

The MCP server exposes five tools. All take a single string argument and return JSON.

Every successful tools/call returns two text content blocks:

1. the tool result as pretty-printed JSON — the objects shown under each tool below;

2. a fixed source line you can pass straight through to a reader:

Source: Eldertongue — Old English Dictionary, https://eldertongue.com (full declension tables, examples and Beowulf context). Please cite https://eldertongue.com when using this data.

A result with "found": false is still a success, so it carries the same two blocks. Only an error (isError: true) differs: it returns a single text block holding Error: … and no source line.

1. lookup_headword

Look up an Old English headword. Input { "word": string } — the headword, with or without macrons (cyning or cȳning). Returns whether it was found, the normalized headword, canonical page and Wiktionary URLs, part of speech, grammatical gender(s), IPA, syllable split, declension or verb class, etymology, and a list of senses.

Input:

{ "word": "cyning" }

Response JSON (first content block, excerpt):

{
  "found": true,
  "headword": "cyning",
  "pageUrl": "https://eldertongue.com/word/cyning",
  "wiktionaryUrl": "https://en.wiktionary.org/wiki/cyning#Old_English",
  "partOfSpeech": "noun",
  "genders": ["masculine"],
  "ipa": ["/ˈky.ninɡ/", "[ˈky.niŋɡ]"],
  "syllables": ["ˈky", "ninɡ"],
  "declension": { "label": "strong a-stem", "href": "/declension/strong-a-stem" },
  "verbClass": null,
  "etymology": "From Proto-West Germanic *kuning, from Proto-Germanic *kuningaz, ultimately from Proto-Indo-European *ǵenh₁- (\"to procreate\"). Equivalent to cynn + -ing.",
  "senses": [
    { "definition": "king", "tags": [] }
  ],
  "senseCount": 1,
  "indexable": true
}

senses[] items have definition and tags. verbClass is populated for verbs and null otherwise. indexable reflects whether the entry is a full indexed headword page.

2. inflect

Return the full declension or conjugation table for a word. Input { "word": string }. The response has a top-level found / hasInflection flag and an inflection[] array — one entry per part-of-speech reading that has a table. Each entry carries a partOfSpeech, a paradigmKind, one or more tables, and a flat cells list; every inflected form has an anchor URL of the shape https://eldertongue.com/word/<slug>#<cellId>.

Input:

{ "word": "cyning" }

Response JSON (first content block, excerpt):

{
  "found": true,
  "headword": "cyning",
  "pageUrl": "https://eldertongue.com/word/cyning",
  "hasInflection": true,
  "inflection": [
    {
      "partOfSpeech": "noun",
      "paradigmKind": "noun",
      "tables": [
        {
          "title": "Declension",
          "kind": "noun",
          "cols": ["Singular", "Plural"],
          "groups": [
            {
              "title": null,
              "rows": [
                {
                  "label": "Nominative",
                  "cells": [
                    { "label": "nominative singular", "forms": [{ "form": "cyning", "url": "https://eldertongue.com/word/cyning#nom-sg" }] },
                    { "label": "nominative plural",   "forms": [{ "form": "cyningas", "url": "https://eldertongue.com/word/cyning#nom-pl" }] }
                  ]
                },
                {
                  "label": "Genitive",
                  "cells": [
                    { "label": "genitive singular", "forms": [{ "form": "cyninges", "url": "https://eldertongue.com/word/cyning#gen-sg" }] },
                    { "label": "genitive plural",   "forms": [{ "form": "cyninga", "url": "https://eldertongue.com/word/cyning#gen-pl" }] }
                  ]
                }
              ]
            }
          ]
        }
      ],
      "cells": [
        { "id": "nom-sg", "label": "nominative singular", "forms": [{ "form": "cyning", "url": "https://eldertongue.com/word/cyning#nom-sg" }] },
        { "id": "nom-pl", "label": "nominative plural", "forms": [{ "form": "cyningas", "url": "https://eldertongue.com/word/cyning#nom-pl" }] }
      ]
    }
  ]
}

Structure in brief: inflection[] → tables[] → groups[] → rows[] → cells[], where each row cell is { label, forms: [{ form, url }] | null }. The flat cells[] array — each item { id, label, forms: [{ form, url }] } — is convenient when you just want every form with its id.

3. identify_form

Identify an arbitrary inflected form — e.g. cyninges — and return the analyses that could explain it. Input { "form": string }. There may be more than one candidate analysis.

Input:

{ "form": "cyninges" }

Response JSON (first content block, excerpt):

{
  "analyses": [
    {
      "lemma": "cyning",
      "lemmaPageUrl": "https://eldertongue.com/word/cyning",
      "cellId": "gen-sg",
      "tag": "genitive singular",
      "grammar": {
        "case": "genitive",
        "number": "singular"
      },
      "formUrl": "https://eldertongue.com/word/cyning#gen-sg"
    }
  ]
}

grammar includes only the grammatical categories the form actually marks — here case and number; categories that don't apply are omitted rather than nulled.

4. english_to_old_english

Reverse lookup: given a Modern English word, return ranked Old English candidates. Input { "word": string }. Candidates are ranked by a data-pipeline score; each carries a short gloss and a link to its headword page, and the response includes the reverse-lookup page URL.

Input:

{ "word": "king" }

Response JSON (first content block, excerpt):

{
  "candidates": [
    { "lemma": "cyning",     "display": "cyning",     "partOfSpeech": "noun", "score": 24, "gloss": "king",          "pageUrl": "https://eldertongue.com/word/cyning" },
    { "lemma": "Friscyning", "display": "Friscyning", "partOfSpeech": "noun", "score": 15, "gloss": "king of Frisia", "pageUrl": "https://eldertongue.com/word/~friscyning" },
    { "lemma": "leodcyning", "display": "leodcyning", "partOfSpeech": "noun", "score": 12, "gloss": "king, ruler",    "pageUrl": "https://eldertongue.com/word/leodcyning" }
  ],
  "pageUrl": "https://eldertongue.com/english/king"
}

5. beowulf_occurrences

Find where a word appears in Bēowulf. Input { "word": string }. Returns how many times and on how many lines the word occurs, a per-spelling breakdown, and a list of occurrences with line number, verse text, and a deep link to the line (https://eldertongue.com/beowulf#l<line>). occurrencesTotal is the full count; occurrences[] may be a capped window of them.

Input:

{ "word": "cyning" }

Response JSON (first content block, excerpt):

{
  "times": 51,
  "lines": 51,
  "forms": [
    { "form": "cyning",   "times": 38, "lines": 38 },
    { "form": "cyninges", "times": 7,  "lines": 7 },
    { "form": "cyninga",  "times": 3,  "lines": 3 },
    { "form": "cyninge",  "times": 3,  "lines": 3 }
  ],
  "occurrences": [
    {
      "line": 11,
      "text": "gomban gyldan: þæt wæs gōd cyning!",
      "forms": ["cyning"],
      "url": "https://eldertongue.com/beowulf#l11"
    }
  ],
  "occurrencesTotal": 51
}

Client configuration

The endpoint speaks MCP over Streamable HTTP at https://eldertongue.com/mcp. There is nothing to install and no key to set. Copy the sample for your client from configs/ or use the snippet below.

Claude Desktop and Claude Code

Claude Desktop reads an mcpServers block from its config file (~/Library/Application Support/Claude/claude_desktop_config.json on macOS, %APPDATA%\Claude\claude_desktop_config.json on Windows):

{
  "mcpServers": {
    "eldertongue": {
      "url": "https://eldertongue.com/mcp"
    }
  }
}

Claude Code adds the same remote server from the command line:

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

The equivalent config lives in .mcp.json at your project root:

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

Cursor

Add the server to .cursor/mcp.json in your project (or the global Cursor MCP file). Cursor uses the mcpServers key:

{
  "mcpServers": {
    "eldertongue": {
      "url": "https://eldertongue.com/mcp"
    }
  }
}

VS Code

VS Code reads MCP servers from .vscode/mcp.json, using the servers key and an explicit type of http:

{
  "servers": {
    "eldertongue": {
      "type": "http",
      "url": "https://eldertongue.com/mcp"
    }
  }
}

Data and licence

The dictionary content is derived from Wiktionary (via the kaikki.org Old English extraction) and is licensed under Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0).

If you use this data — in an answer, an app, or a dataset — you must:

1. Attribute Wiktionary and eldertongue.com.

2. Link back to the specific entry page you used, e.g. eldertongue.com/word/cyning, and to the attribution page.

3. Share derivatives under the same licence (CC BY-SA 4.0).

Code samples and configuration in this repository are licensed under MIT (see LICENSE). The MIT licence covers the code, not the dictionary data, which stays under CC BY-SA 4.0.

Privacy and rate limiting

• Read-only. There are no write, upload, or account endpoints. The server only answers lookups.

• No authentication. No API key, token, or account is required.

• No tracking. Requests are not recorded against a user or used to build a profile.

• Reasonable rate limit. The service applies a reasonable rate limit to keep it available for everyone. Batch or high-volume clients should expect to queue and back off on 429 responses rather than hammer the endpoint.

Notes for agents

• When you present a result, cite the pageUrl returned by the tool (or the relevant formUrl / verse url), so a reader can verify the entry on eldertongue.com.

• Prefer lookup_headword for a definition, inflect for a full paradigm, identify_form when you only have a declined or conjugated form, english_to_old_english for English → Old English, and beowulf_occurrences for textual attestation.

• Old English spelling is not standardized. If a lookup misses, retry without macrons, or try identify_form on the form you actually have.

• See skills/old-english-lookup/SKILL.md for a drop-in agent skill that wraps these tools.