@cyanheads/openalex-mcp-server

Public Hosted Server: https://openalex.caseyjhand.com/mcp

Overview

Scholarly catalog data from OpenAlex — 270M+ works, 90M+ authors, 100K+ sources, plus institutions, topics, keywords, publishers, funders, and awards. Search, filter, and aggregate across all nine entity types, resolve ambiguous names to canonical IDs, and walk the citation graph one hop at a time.

Tools

Prompts

The server also publishes an agent skill, openalex-guide (skill://openalex-guide/SKILL.md, source in skills/openalex-guide/): which filter key answers the question, how to read group_by counts, where each ID type comes from, and how to pin an author without picking a namesake. It ships in the npm package, the Docker image, the .mcpb bundle, and plugin installs.

Related MCP server: mcp-openalex

Capability reference

openalex_search_entities tool

• Retrieve a single entity by id: an OpenAlex ID, DOI, ORCID, ROR, PMID, ISSN, or PMCID, bare or as a URL (OpenAlex record-page and API URLs such as https://openalex.org/works/W2741809807 included), or a keyword by its slug or URL. Under entity_type: "funders", a Crossref Funder Registry DOI (10.13039/…) also resolves

  • id takes precedence: search parameters passed alongside it are dropped, and the response names which ones

  • Lookups by ID are unbilled, except a keyword slug or URL, an id with characters past the identifier (W2741809807#x still returns W2741809807), and a funder DOI, which each bill as one list call

  • Fails before any request as id_type_mismatch (an OpenAlex ID of another entity type) or id_dot_segment (a . or .. path segment); a ?, #, \, tab, or line break inside an identifier is percent-encoded, so SICI DOIs ending in # resolve

  • A PMCID resolves nothing (OpenAlex indexes none); use the work's PMID or DOI

• entity_type: "awards" reaches grants (G… IDs), which openalex_resolve_name does not look up since OpenAlex has no award autocomplete

• Keyword search (boolean operators, quoted phrases, wildcards, fuzzy match) plus exact and semantic search modes — semantic ranks a query-dependent candidate set at ~1 req/sec (up to 50 per page), and its meta.count reports the candidate count rather than a match total

• filters accepts a record object or an unambiguous native string ("issn:0920-8542"), including through the filter alias. Conversion is disclosed in notice; commas outside paired double quotes separate clauses, and the first colon separates a key from its value, preserving DOI/URL colons and quoted comma phrases. Exact duplicate keys, bare fragments, and unmatched quotes are rejected with record-form recovery guidance. A record holds one value per key; distinct aliases of the same upstream field still AND together. Set OPENALEX_FILTER_STRING_INPUT=false to require record objects. Native strings apply only to this tool's filters, with the record form remaining the advertised schema

• Filter values sent unquoted must have paired double quotes on all four filter-taking tools (unmatched_quote_in_filter_value); citation filters are checked before the seed lookup. Balanced search phrases such as "graph neural" networks remain valid, including .search.exact. A value sent double-quoted still cannot contain its own interior double quote (quote_in_filter_value)

• Rich filter syntax: AND across fields, OR within a field (|), AND within a field (+), NOT (!), ranges, comparisons

  • One value cannot mix | with an AND (a +, or a space between IDs or codes): OpenAlex would silently drop the AND-ed alternatives, so DE|FR+US and authorships.author.id: A1 A2|A3 fail as mixed_and_or_in_filter_value before any request. Put the AND in a second key instead (institutions.country_code: US beside authorships.institutions.country_code: DE|FR on works)

  • Fields OpenAlex matches as whole text (display_name, awards.funder_display_name, awards.funder_award_id, geo.city, geo.region, raw_affiliation_strings, block_key, biblio fields) are sent double-quoted, so a value with spaces or commas matches as one phrase (awards.funder_display_name: National Science Foundation). ! and | still work (geo.city: New York|Boston); + cannot AND it with another value

  • A comma is allowed in .search values and whole-text fields; anywhere else it fails as comma_in_filter_value (use | for OR)

  • + is a literal character in .search values, DOIs, dates, URLs, exactly matched names (C++, Erasmus+), biblio fields (issue 1+2), and awards.funder_award_id

  • A double quote inside a value sent quoted fails as quote_in_filter_value

• Country and language values are converted to the codes OpenAlex stores, in every tool that takes filters:

  • Country fields (keys ending in country_code, country_codes, or countries): ISO alpha-3 codes, numeric codes, and English names (ISO's or OpenAlex's own facet labels, such as Ivory Coast) become alpha-2 (DEU, 276, Germany → DE; UK → GB). A value that cannot be a country (Germanyy, 999, DE US) fails as invalid_country_code before any request

  • language: ISO 639-2 codes and English names become ISO 639-1 (eng, English → en; Cebuano → ceb)

  • Each |/+ segment converts on its own (South Korea|Japan → KR|JP); anything else (null, XK, zh-cn, the countries/DEU path form) is sent as given

• select returns a curated per-entity-type default unless overridden, or ["*"] for the full record; invalid field names error with the valid set. On works, author_list returns each author in authorship order as {id, display_name, orcid} — about a tenth the size of authorships, which adds institutions and affiliations — and is never part of the default or ["*"]

• Cursor pagination for keyword and exact search, up to 100 results per page (default 25); semantic search walks its candidates with page (1-based) instead, up to 50 per page, and mixing either knob with the wrong search_mode is rejected before the upstream call

• sample (up to 10,000) plus a deterministic seed for reproducible random sampling; keyword and exact modes only, and never alongside sort or cursor — OpenAlex does not sample a semantic search and refuses a sorted sample, so those combinations are rejected before the upstream call. per_page defaults to min(sample, 100), so a sample of 100 or fewer returns whole in one call; a larger one is walked with page and a seed (sample_page_without_seed without one), up to record 10,000 (sample_page_too_deep past it)

• A page is per_page records, whole, and an id lookup returns every selected array whole; slice: {field, offset, limit} on an id lookup pages one array by count (limit default 50, clamped to 5,000). A response over 8,000,000 bytes on either surface (structuredContent, or content[] text) fails as response_too_large and names a per_page or slice.limit that fits, or a narrower select

• A list record carrying exactly 100 authorships or author_list entries is flagged as possibly capped, with an id + slice call to retrieve more stored authors. Singleton lookups and snapshots retain at most 5,000 authorships per work; at that ceiling both author fields remain possibly capped on every slice. total counts stored entries rather than a complete byline, and next becomes null when those entries are exhausted. Another OpenAlex fetch or snapshot cannot recover authors beyond the storage ceiling

• Oversized positive integers clamp to their cap, with requested/applied sizes in notice, a log, and a counter: per_page above 100 (200 on analysis, 50 under semantic search), slice.limit above 5,000, and sample above 10,000. Set OPENALEX_CLAMP_PER_PAGE=false to reject each over its cap instead. Zero, negatives, and fractions always reject. An id ignores page size

• display_name is nullable for untitled records; every call reports OpenAlex daily-budget cost and remaining balance

openalex_analyze_trends tool

• Group any supported field for trend, distribution, or comparative analysis; combine with filters to scope the population before aggregation

• Up to 200 groups per page (default). Without a cursor, order: "count" (default) returns the top-N by count with no further pages; order: "key" enumerates distinct values key-ascending with cursor pagination. Boolean fields keep count order even with "key" and do not support cursor pagination. A supplied cursor selects key order even when order is omitted or "count". OpenAlex can wrap a key-ordered walk to earlier groups: stop when a page's first key repeats an earlier key, or when a page is short or empty, even if next_cursor is still present

• include_unknown (default false) adds a group for entities with no value for the grouped field, flagged is_unknown: true and labeled as unknown in the text output. The native :include_unknown suffix on group_by also enables it, even with an explicit false; passing both adds the suffix once. OpenAlex keys it -111/-111.0 (numeric fields), unknown (text fields and order: "key"), or an ID ending in /unknown; the key is a sentinel, not a filter value. Boolean fields have no such group — a missing value counts as false

• key_display_name remains present but can be null when OpenAlex supplies no label; text output renders the group key in that case, including unknown buckets

• Not every field is groupable — raw date fields, .search operators, from_*/to_* range modifiers, decimal scores such as fwci, display_name, external-ID fields such as doi, and fields OpenAlex looks up from a related entity such as primary_location.source.country_code are rejected; openalex_describe_fields(entity_type, "group_by") lists the fields that group

• A works group_by on authorships.countries says in its notice that OpenAlex counts only each work's first 100 authorships for that field, and names authorships.institutions.country_code as the field that counts all of them

• entity_type: "awards" groups by fields such as start_year, funder.id, or funding_type; groups count awards and do not sum amount_usd

• Reports OpenAlex daily-budget cost and remaining balance — aggregation is priced far below paging the same entities

openalex_resolve_name tool

• A name or partial name runs an autocomplete search over works, authors, sources, institutions, topics, keywords, publishers, and funders: up to 10 matches with disambiguation hints (last institution, host organization, place, etc.)

• An award ID (G…, bare or as an OpenAlex URL) sends no request: OpenAlex has no award autocomplete, so the response is empty with a notice naming the openalex_search_entities call that opens the award. Under an explicit entity_type, a bare G… is searched as a name of that type

• An identifier — OpenAlex ID, DOI, ORCID, ROR, PMID, ISSN, or keyword URL, bare or in URL form — resolves directly to the record it addresses, as the entity type it belongs to. A ROR can name an organization's institution, funder, and publisher records at once: with no entity_type (or any other type) all three are looked up in parallel as unbilled singleton fetches and every record found is returned, institution first; entity_type institutions, funders, or publishers narrows it to that one. A Crossref Funder Registry DOI (10.13039/…) resolves to the funder unless entity_type is works. A PMCID is recognized but resolves nothing — OpenAlex indexes none

• Short names share the bare OpenAlex ID shape (keyword p53 reads as publisher P53), so a bare OpenAlex ID that resolves nothing is searched as a name next, under entity_type when given, and the notice names both outcomes; a real ID still resolves with its one request. Under entity_type: "keywords" the shape is searched as a keyword name from the start

• filters narrows autocomplete only and requires entity_type — a name query passing filters without it is rejected before any request (filters_without_entity_type). On an identifier lookup they're ignored and named in a notice; a name search that matches nothing under filters echoes them and suggests loosening them first

• With entity_type set, OpenAlex autocomplete fails on a name over 1,000 characters; that failure is reported once as query_too_long with advice to shorten the name, not retried as an outage

• Reports OpenAlex daily-budget cost and remaining balance

openalex_get_citation_graph tool

• direction sets the edge: cites (works citing the seed), cited_by (the seed's own reference list), related_to (OpenAlex's algorithmic related works, ~8-30 typical, may be empty)

• seed_id accepts an OpenAlex work ID (bare, or its OpenAlex record-page or API URL), DOI, or PMID (PMCID recognized but resolves nothing); validated against a live lookup first, so a non-existent seed fails as NotFound rather than returning an empty graph, and the ID of another entity type fails as id_type_mismatch before any upstream call

• Stacks with filters/sort/select (author_list included) to narrow the graph; filters cannot set cites/cited_by/related_to, nor an alias of one such as cited_works — those keys are reserved for direction

• Cursor pagination, up to 100 results per page (default 25); a page is per_page works, whole

• The same 8,000,000-byte response_too_large failure (naming a per_page that fits) and 100-authorship cap disclosure as openalex_search_entities

• Reports OpenAlex daily-budget cost, covering both the seed-validation lookup and the graph page, plus remaining balance

openalex_describe_fields tool

• Lists every valid field name for an entity type + context (filter, group_by, select) — the complete pool, never truncated

• group_by is the filter set minus what OpenAlex rejects as an aggregation key: raw date fields, .search/.search.exact operators, from_*/to_* range modifiers, and a per-entity-type set found by grouping every listed field against the live API — decimal scores such as fwci, several source year fields, display_name, and external-ID fields among them

• created_date, updated_date, and their from_/to_ forms are listed filters that OpenAlex serves only on a paid plan; without one, a filter on them fails on its first request as upstream_plan_required, with no retry

• Optional query reorders results by name similarity without dropping any field — a nested value's parent object stays reachable further down the list

• Backed by a generated field catalog — no live API calls

openalex_literature_review prompt

• Arguments: topic required; scope (narrow / broad) optional, defaults to narrow

• Returns one user message walking a 6-step workflow: resolve entities, search literature, identify key papers, trace citations, analyze the landscape, synthesize findings

• scope changes the search step: narrow favors exact search with tight topic filters; broad adds semantic search across multiple related topic IDs

openalex_research_landscape prompt

• Arguments: topic required

• Returns one user message walking a 7-step quantitative workflow: resolve the topic ID, volume trends, top contributors (institutions/countries/journals), open access rate, funding sources, most-cited works, emerging fronts

• The funding step groups by funders.id, which counts every work that lists a funder and labels each group with the funder's name; for grants it groups the topic's works by awards.id and opens the top G… IDs on entity_type: "awards" for amounts and dates, since few awards carry a topic of their own

Features

Built on @cyanheads/mcp-ts-core: stdio and Streamable HTTP transports, pluggable auth (none / jwt / oauth), swappable storage (in-memory, filesystem, Supabase, Cloudflare KV/R2/D1), structured logging with optional OpenTelemetry tracing.

OpenAlex-specific:

• Typed API client with automatic ID normalization (DOI, ORCID, ROR, PMID, PMCID, ISSN, OpenAlex record-page and API URLs over http, https, or no scheme, PubMed/PubMed Central URLs); a PMCID normalizes but resolves nothing since OpenAlex indexes none

• Keyless by default — an optional API key raises rate and daily-budget limits, and an optional mailto identifies the caller to OpenAlex's polite pool

• HTTP status codes mapped to specific MCP error classes (400 → InvalidParams, or ServiceUnavailable when a semantic search's query embedding failed upstream; 422 → ValidationError; 429 → RateLimited, or Forbidden when the 429 refuses a paid-plan filter) with upstream messages surfaced

• Timeout-aware request retries and cancellation support via AbortSignal

Agent-friendly output:

• Provenance — every API-calling tool reports OpenAlex daily-budget cost, remaining balance, and reset time (budget.costUsd, remainingUsd, resetsInSeconds)

• Effective-query echo — search, trends, and citation-graph responses echo the criteria that actually ran, so an empty result is diagnosable without re-reading the request

• Discriminated output contracts — typed error reasons (entity_not_found, upstream_budget_exhausted, semantic_per_page_cap, reserved_filter_key, and more) each carrying an explicit recovery hint

• Response shaping — abstracts are reconstructed from OpenAlex's inverted-index encoding into plaintext, and display_name stays null for untitled or paratext records instead of being backfilled

• Clean provider text — OpenAlex passes titles, abstracts, and names through unsanitized; HTML entities are decoded against the full WHATWG table, comments and HTML/JATS/MathML formatting tags are removed, CDATA wrappers and IOP's <?CDATA …?> math markers are unwrapped with their TeX kept, MathType equation blobs (% MathType!MTEF!…!44A1!) are removed while the TeX that restates them stays, and a double-escaped line break (a literal \n) becomes a space; literal text such as A < B, 95% CI, and TeX such as \nu is kept. Identifier and URL fields (id, doi, ids, orcid, ror, issn, *_url, lineages) are returned exactly as OpenAlex stores them, so each one resolves when passed back. The text output escapes that text for Markdown, so a stray *, <tag>, or [x](y) renders as written, and line breaks, tabs, and leading or trailing spaces read back as the structured output holds them; a multi-line display_name renders on its own **Display Name:** line. Notices escape caller text the same way. IDs, and URLs that render as links, stay byte-identical

Getting started

Connect to the hosted instance, no install:

claude mcp add --transport http openalex-mcp-server https://openalex.caseyjhand.com/mcp

Or run it locally:

claude mcp add openalex-mcp-server -- npx -y @cyanheads/openalex-mcp-server

For other clients, add this to the MCP config file:

{
  "mcpServers": {
    "openalex-mcp-server": {
      "command": "npx",
      "args": ["-y", "@cyanheads/openalex-mcp-server"]
    }
  }
}

An optional OPENALEX_API_KEY — a free OpenAlex account key — raises the rate limits and daily budget over anonymous access; OPENALEX_MAILTO identifies you to OpenAlex's polite pool. For Docker or a source build, see Running the server.

Configuration

See .env.example for the full list of optional overrides.

Running the server

Local development

Requires Bun v1.4.0 or higher (or Node.js v24+).

• Clone and install:

  git clone https://github.com/cyanheads/openalex-mcp-server.git
  cd openalex-mcp-server && bun install
  cp .env.example .env   # optionally set OPENALEX_API_KEY

• Build and run:

  # One-time build
  bun run rebuild
  
  # Run the built server
  bun run start:stdio
  # or
  bun run start:http

• Run checks and tests:

  bun run devcheck   # Lints, formats, type-checks
  bun run test       # Runs the test suite

Docker

docker run --rm -e OPENALEX_API_KEY=your-key -p 3010:3010 ghcr.io/cyanheads/openalex-mcp-server:latest

The image defaults to HTTP transport, stateless session mode, and logs to /var/log/openalex-mcp-server. To run it over stdio from an MCP client, use "command": "docker" with "args": ["run", "-i", "--rm", "-e", "MCP_TRANSPORT_TYPE=stdio", "ghcr.io/cyanheads/openalex-mcp-server:latest"]. To build locally, docker build -t openalex-mcp-server .; OpenTelemetry peer dependencies are installed by default — build with --build-arg OTEL_ENABLED=false to omit them.

Project structure

Development guide

See CLAUDE.md for development guidelines and architectural rules. The short version:

• Handlers throw, framework catches — no try/catch in tool logic

• Use ctx.log for logging, ctx.state for storage

• Wrap OpenAlex responses: validate the raw payload → normalize to a domain type → return the output schema; never fabricate missing fields

• Always resolve names to IDs via openalex_resolve_name before filtering by entity

Contributing

Issues are welcome. Run checks before submitting:

bun run devcheck
bun run test

License

Apache-2.0 — see LICENSE for details.