openpapers-mcp

Overview Schema Source Related Servers Discussions Admin

find_oa_pdf

Find a legal open access PDF for any DOI. Returns the OA status and direct download URLs.

Instructions

Find a legal Open Access PDF for a DOI via Unpaywall. Returns the OA status, the best OA location (with direct PDF URL if available), and a list of all OA locations (repository vs publisher, version, license).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "doi": "<doi>"
    },
    "name": "find_oa_pdf"
  }
}

Input Schema

Name	Required	Description	Default
`doi`	Yes	DOI of the paper (bare, URL, or 'doi:' prefix accepted).

Output Schema

Name	Required	Description	Default
`doi`	No
`genre`	No
`is_oa`	Yes
`pdf_url`	No
`oa_status`	No
`journal_name`	No
`oa_locations`	No
`journal_is_oa`	No
`best_oa_location`	No
`journal_is_in_doaj`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 29, 2026

TDQS

A4/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden. It discloses return values (OA status, best location, list of locations) and the data source, but does not mention read-only behavior, failure handling, or authorization requirements. This is adequate but not thorough.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loaded with the main purpose, and every word adds value. There is no redundancy or unnecessary detail.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the simple single-parameter signature and the presence of an output schema, the description provides a complete account of the tool's function and return structure. It lacks explicit usage guidance relative to siblings, but that is not critical for this simple tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema provides 100% coverage for the 'doi' parameter, including acceptable formats. The description adds no extra parameter-specific meaning beyond the schema, so the baseline score of 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's function: find a legal Open Access PDF for a given DOI via Unpaywall. It uses a specific verb and resource, and the distinction from sibling tools like search_papers and download_pdf is clear.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies the tool is used when you have a DOI and need a legal Open Access PDF. It does not explicitly mention alternatives or exclusions, but the context is clear enough for an agent to decide when to invoke it.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server