paper_search · REST + MCP

Search academic papers

Search scholarly papers, articles, books and preprints by topic or title: title, authors, year, journal or venue, DOI, link, type and citation count (metadata only, no abstracts). Use it to find sources or citations for a research question. Data source: Crossref.

$0.002 USD per successful paid call

Free to try. A few calls a day over MCP without a key. Daily limits apply; with a key, calls use the price above.

Charged once per call that returns a result, including an empty result list. Failed calls are free.

Connect your agent

Use it in your chat

Start with no key

In Claude.ai, Claude Desktop, Claude Code, ChatGPT or Codex, add a custom connector with this URL. No API key or Authorization header is needed.

https://unstuckapi.com/mcp

Try a few free calls a day with read_page, domain_check, domain_info, pdf_to_text, vulnerability_lookup, or paper_search. Each free result says how many are left and when they reset (midnight UTC).

A paid tool called without a key returns a new API key and a payment link instead of a result, and nothing is charged. In Claude, a Connect button opens the same payment page. Once credit is added, the agent can continue in the same chat with that key.

Already have a key?

If your connector cannot send headers, use this URL instead. Replace YOUR_API_KEY with your key.

https://unstuckapi.com/mcp?key=YOUR_API_KEY

Keep the completed URL private: it contains your API key.

Ask your agent to call paper_search with these arguments:

{
  "query": "large language model agents",
  "limit": 5
}

Inputs

Send these fields as a JSON object to POST /v1/tools/paper_search.

Input fields for paper_search
Field	Type	Description & limits
`query`	string Required	What to search for, e.g. "microplastics drinking water".Minimum characters: 2 · Maximum characters: 300
`limit`	integer Optional	How many papers, default 5, max 10.Minimum: 1 · Maximum: 10
`from_year`	integer Optional	Only works published in or after this year.Minimum: 1600 · Maximum: 2100

Developer option: REST

Replace YOUR_API_KEY with your key. The following command makes a paid call if it succeeds.

export UNSTUCK_API_KEY="YOUR_API_KEY"

curl 'https://unstuckapi.com/v1/tools/paper_search' \
  -H "Authorization: Bearer $UNSTUCK_API_KEY" \
  -H 'Content-Type: application/json' \
  --data '{"query":"large language model agents","limit":5}'

The response contains result, charged_usd, and your remaining balance_usd. Invalid input and failed tool calls are not charged.

Developer option: MCP with a header

For clients that support headers, connect using Streamable HTTP and these values:

https://unstuckapi.com/mcp

Authorization: Bearer YOUR_API_KEY

Connection guide · Full JSON schemas and prices · Agent instructions