Agent skill

Crossref API

by wentorai in wentorai/research-plugins

Resolve DOIs and retrieve publication metadata from CrossRef registry

Install Crossref API

skills CLI

$ npx skills add wentorai/research-plugins --skill crossref-api -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install wentorai/research-plugins crossref-api --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/literature/metadata/crossref-api .claude/skills/crossref-api && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "crossref-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/crossref-api into .claude/skills/crossref-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "crossref-api", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/crossref-api

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add wentorai/research-plugins --skill crossref-api -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install wentorai/research-plugins crossref-api --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/literature/metadata/crossref-api .agents/skills/crossref-api && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "crossref-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/crossref-api into .agents/skills/crossref-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "crossref-api", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add wentorai/research-plugins --skill crossref-api -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install wentorai/research-plugins crossref-api --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/literature/metadata/crossref-api .cursor/skills/crossref-api && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "crossref-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/crossref-api into .cursor/skills/crossref-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "crossref-api", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/wentorai/research-plugins.git --path skills/literature/metadata/crossref-api

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add wentorai/research-plugins --skill crossref-api -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install wentorai/research-plugins crossref-api --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/literature/metadata/crossref-api .gemini/skills/crossref-api && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "crossref-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/crossref-api into .gemini/skills/crossref-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "crossref-api", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install wentorai/research-plugins crossref-api

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add wentorai/research-plugins --skill crossref-api -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/literature/metadata/crossref-api .github/skills/crossref-api && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "crossref-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/crossref-api into .github/skills/crossref-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "crossref-api", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add wentorai/research-plugins --skill crossref-api -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install wentorai/research-plugins crossref-api --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/literature/metadata/crossref-api .opencode/skills/crossref-api && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "crossref-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/crossref-api into .opencode/skills/crossref-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "crossref-api", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: crossref-api
GitHub stars: 298
Used in: 1 other repo
Token cost: ~1.5k tokens
SKILL.md length: 520 words
Files: 1
Skills in repo: 428
Repo updated: Jun 19, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Resolve DOIs and retrieve publication metadata from CrossRef registry

Tasks that involve Citation management
SKILL.md covers Overview, Authentication, Core Endpoints and Rate Limits, plus 2 more sections
Calls curl and jq; reaches api.crossref.org

What it does

Crossref API is an agent skill from wentorai/research-plugins. Resolve DOIs and retrieve publication metadata from CrossRef registry

Its SKILL.md is about 1.5k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Backend & APIs, covering Citation management. The repository describes itself as: 350+ academic research skills, MCP configs, and plugins for Research-Claw and AI agents. The licence is MIT.

When your agent uses it

Tasks that involve Citation management

Example prompts

“/crossref-api”

What it can do on your machine

Read from SKILL.md and the folder at commit bf44b3c. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
- curl
- jq
From the folder's file list and the shell code blocks in SKILL.md.
Network
Hosts in commands or code, which the agent is likely to contact:
- api.crossref.org
Also links to:
- crossref.org
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Crossref API loads about 1.5k tokens when it runs. Until then it costs about 21 tokens; SKILL.md has 520 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~21
When it runs · the whole SKILL.md, loaded when a task matches: ~1.5k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from wentorai/research-plugins at commit bf44b3c, republished under its MIT licence (© wentorai). 520 words, ~1,475 tokens.

Download SKILL.mdSave it as .claude/skills/crossref-api/SKILL.md (or your agent's skills folder).

name: crossref-api
description: Resolve DOIs and retrieve publication metadata from CrossRef registry

CrossRef API Guide

Overview

CrossRef is the official DOI registration agency for scholarly publishing, maintaining metadata for over 150 million content items including journal articles, books, conference proceedings, preprints, and datasets. The CrossRef REST API provides free, open access to this metadata, making it the authoritative source for resolving Digital Object Identifiers (DOIs) and retrieving standardized publication records.

Publishers deposit metadata with CrossRef when they register DOIs for their content. This makes the CrossRef API a reliable source for bibliographic information, citation counts, licensing data, funder acknowledgments, and links to full-text resources. The API is used extensively in reference management, citation analysis, and research information systems.

The API is free and requires no authentication. Users who include a mailto parameter in their requests are placed in the "polite pool" which provides faster and more reliable service.

Authentication

No authentication required. For best performance, include your email to access the polite pool:

https://api.crossref.org/works?mailto=your@email.com

Users in the polite pool receive prioritized responses and are not subject to the same rate limiting as anonymous users. CrossRef Plus subscribers get additional benefits including guaranteed uptime and higher throughput.

Core Endpoints

Works: Query Publication Metadata

URL: GET https://api.crossref.org/works

Parameters:

Param	Type	Required	Description
query	string	No	Free-text query across all metadata fields
query.title	string	No	Search specifically in titles
query.author	string	No	Search specifically by author name
filter	string	No	Structured filters (e.g., from-pub-date:2024, type:journal-article)
sort	string	No	Sort field: relevance, published, is-referenced-by-count
order	string	No	asc or desc
rows	integer	No	Results per page (default: 20, max: 1000)
offset	integer	No	Pagination offset
mailto	string	No	Email for polite pool

Example:

bash

curl "https://api.crossref.org/works?query.title=attention+is+all+you+need&rows=5&mailto=user@example.com"

Response: JSON with message.items array containing DOI, title, author, published, is-referenced-by-count, reference, license, and link fields.

Works by DOI: Direct DOI Resolution

URL: GET https://api.crossref.org/works/{doi}
Parameters:
Param Type Required Description
doi string Yes The DOI to resolve (URL path parameter)
mailto string No Email for polite pool

Param	Type	Required	Description
doi	string	Yes	The DOI to resolve (URL path parameter)
mailto	string	No	Email for polite pool

Example:

bash

curl "https://api.crossref.org/works/10.1038/s41586-021-03819-2?mailto=user@example.com"

Response: JSON with complete metadata record for the DOI, including all registered bibliographic information.

Show full SKILL.md (198 more words)Show less

Members: Publisher Information

URL: GET https://api.crossref.org/members
Parameters:
Param Type Required Description
query string No Publisher name search
rows integer No Results per page

Param	Type	Required	Description
query	string	No	Publisher name search
rows	integer	No	Results per page

Example:

bash

curl "https://api.crossref.org/members?query=springer&rows=5&mailto=user@example.com"

Response: JSON with publisher metadata including member ID, name, prefix list, and coverage statistics.

Journals: Journal Metadata

URL: GET https://api.crossref.org/journals
Parameters:
Param Type Required Description
query string No Journal title search
rows integer No Results per page

Param	Type	Required	Description
query	string	No	Journal title search
rows	integer	No	Results per page

Example:

bash

curl "https://api.crossref.org/journals?query=nature+machine+intelligence&rows=5&mailto=user@example.com"

Response: JSON with journal information including ISSN, title, publisher, subject, and coverage counts.

Rate Limits

Anonymous users: no hard limit but throttled under load. Polite pool users (with mailto): prioritized access with no published rate cap. CrossRef Plus subscribers: guaranteed uptime with SLA. The API returns HTTP 429 when overloaded. Use exponential backoff and always include mailto for production applications. For bulk metadata retrieval, CrossRef provides database snapshots and the Public Data File.

Common Patterns

Validate and Enrich a Reference List

Resolve a list of DOIs to get standardized metadata:

bash

# Single DOI resolution with full metadata
curl "https://api.crossref.org/works/10.1145/3292500.3330672?mailto=user@example.com"

Find Recent Highly-Cited Papers in a Field

Filter by publication date and sort by citation count:

bash

curl "https://api.crossref.org/works?filter=from-pub-date:2023,type:journal-article&query=machine+learning&sort=is-referenced-by-count&order=desc&rows=20&mailto=user@example.com"

Track Citation Growth

Monitor citation counts for a specific DOI over time:

bash

curl "https://api.crossref.org/works/10.1038/s41586-021-03819-2?mailto=user@example.com" | jq '.message["is-referenced-by-count"]'

References

Official documentation: https://api.crossref.org
API documentation: https://api.crossref.org/swagger-ui/index.html
CrossRef metadata best practices: https://www.crossref.org/documentation/

Files

Just SKILL.md in skills/literature/metadata/crossref-api of wentorai/research-plugins.

Open the folder on GitHubat commit bf44b3c

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in wentorai/research-plugins, which our catalogue first saw on October 7, 2026.

brycewang-stanford/Auto-Empirical-Research-Skillsskills/43-wentorai-research-plugins/skills/literature/metadata/crossref-api

Compare with similar skills

Crossref API next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Crossref API compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Crossref API this skillwentorai/research-plugins	298	1 repos	~1.5k	Automated safety check: Pass	MIT	3 mo ago
Octo SummaryMininglamp-OSS/octo-cli	918	—	~1k	Automated safety check: Pass	Apache-2.0	8 days ago
Goosetown Researcher GitHubaaif-goose/goosetown	154	—	~1.6k	Automated safety check: Pass	Apache-2.0	3 mo ago
Collaborating With Geminiappautomaton/latex-arxiv-SKILL	457	1 repos	~1.1k	Automated safety check: Pass	MIT	23 days ago
Sciverseopendatalab/Sciverse-Agent-Tools	119	—	~3k	Automated safety check: Pass	Custom licence	17 days ago
Research Lookupdavila7/claude-code-templates	32k	10 repos	~5k	Automated safety check: Notes	MIT	today

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Questions about Crossref API

What does Crossref API do?

Resolve DOIs and retrieve publication metadata from CrossRef registry. Crossref API is an agent skill from wentorai/research-plugins.

When should I use Crossref API?

Crossref API fits situations like: tasks that involve Citation management.

How do I install Crossref API in Claude Code?

Run `npx skills add wentorai/research-plugins --skill crossref-api -a claude-code`. Or copy the skill folder (skills/literature/metadata/crossref-api in wentorai/research-plugins) into .claude/skills/crossref-api in your project. Claude Code loads it when a task matches its description.

How do I install Crossref API in Codex?

Run `npx skills add wentorai/research-plugins --skill crossref-api -a codex`. Or copy the skill folder (skills/literature/metadata/crossref-api in wentorai/research-plugins) into .agents/skills/crossref-api in your project. Codex loads it when a task matches its description.

Can I use Crossref API in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add wentorai/research-plugins --skill crossref-api -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/crossref-api, .gemini/skills/crossref-api, .github/skills/crossref-api and .opencode/skills/crossref-api in your project.

What does Crossref API need to run?

Going by SKILL.md and its folder, Crossref API needs the command-line tools its instructions call (curl and jq).

Does Crossref API access the network?

SKILL.md names 2 domains. In commands or code: api.crossref.org; the agent is likely to contact it when it follows the instructions. As links in the text: crossref.org. This is read from the text; nothing was executed.

Is Crossref API safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Crossref API use?

Crossref API is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Crossref API use?

About 1.5k tokens (SKILL.md is roughly 5.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Crossref API?

Skills that share tags, products or a category with Crossref API: Octo Summary (Mininglamp-OSS/octo-cli, 918 stars), Goosetown Researcher GitHub (aaif-goose/goosetown, 154 stars), Collaborating With Gemini (appautomaton/latex-arxiv-SKILL, 457 stars) and Sciverse (opendatalab/Sciverse-Agent-Tools, 119 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Crossref API?

wentorai (a GitHub user) maintains it in wentorai/research-plugins, which has 298 GitHub stars. The repository holds 428 skills in this directory. The repository was last updated on June 19, 2026.

Source: wentorai/research-plugins on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Crossref API

Facts

At a glance

What it does

When your agent uses it

Example prompts

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

CrossRef API Guide

Overview

Authentication

Core Endpoints

Works: Query Publication Metadata

Works by DOI: Direct DOI Resolution

Members: Publisher Information

Journals: Journal Metadata

Rate Limits

Common Patterns

Validate and Enrich a Reference List

Find Recent Highly-Cited Papers in a Field

Track Citation Growth

References

Files

Used in 1 other repository

Compare with similar skills

Similar skills

More from wentorai/research-plugins

Related

Questions about Crossref API