Unpaywall

Get Oa

get_oa

Read-onlyIdempotent

Given a DOI, fetch open-access status and the best free legal copy if one exists. Returns is_oa, oa_status (gold | green | hybrid | bronze | closed), best location (URL, host type, license), and journal metadata.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`doi`	Yes	DOI (e.g., "10.1038/nature12373")

Output Schema

TableJSON Schema

Name	Required	Description
`doi`	Yes	Digital Object Identifier
`year`	Yes	Publication year
`genre`	Yes	Publication type (journal-article, etc.)
`is_oa`	Yes	Is open-access version available
`title`	Yes	Paper title
`authors`	Yes	List of author names
`doi_url`	Yes	DOI resolver URL
`oa_status`	Yes	OA category: gold, green, hybrid, bronze, or closed
`publisher`	Yes	Publisher name
`journal_name`	Yes	Journal name
`best_location`	Yes
`journal_is_oa`	Yes	Is the entire journal open-access
`journal_issns`	Yes	Journal ISSN(s)
`published_date`	Yes	Publication date
`journal_in_doaj`	Yes	Is journal in DOAJ directory
`other_locations`	Yes	Alternative free access locations
`has_repository_copy`	Yes	Available in institutional repository

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedMay 22, 2026

addedInput schema / examples

Added value: +[
+  {
+    "doi": "10.1038/nature12373"
+  },
+  {
+    "doi": "10.1371/journal.pmed.1002295"
+  }
+]

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "authors": {
+      "description": "List of author names",
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "best_location": {
+      "properties": {
+        "evidence": {
+          "description": "How OA status was determined",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "host_type": {
+          "description": "Host type: publisher, repository, etc.",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "license": {
+          "description": "License type (CC-BY, etc.)",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "pdf_url": {
+          "description": "Direct PDF URL if available",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "repository": {
+          "description": "Repository institution name",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "url": {
+          "description": "Access URL for full text",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "version": {
+          "description": "Version: published, accepted, submitted",
+          "type": [
+            "string",
+            "null"
+          ]
+        }
+      },
+      "type": [
+        "object",
+        "null"
+      ]
+    },
+    "doi": {
+      "description": "Digital Object Identifier",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "doi_url": {
+      "description": "DOI resolver URL",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "genre": {
+      "description": "Publication type (journal-article, etc.)",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "has_repository_copy": {
+      "description": "Available in institutional repository",
+      "type": [
+        "boolean",
+        "null"
+      ]
+    },
+    "is_oa": {
+      "description": "Is open-access version available",
+      "type": "boolean"
+    },
+    "journal_in_doaj": {
+      "description": "Is journal in DOAJ directory",
+      "type": [
+        "boolean",
+        "null"
+      ]
+    },
+    "journal_is_oa": {
+      "description": "Is the entire journal open-access",
+      "type": [
+        "boolean",
+        "null"
+      ]
+    },
+    "journal_issns": {
+      "description": "Journal ISSN(s)",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "journal_name": {
+      "description": "Journal name",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "oa_status": {
+      "description": "OA category: gold, green, hybrid, bronze, or closed",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "other_locations": {
+      "description": "Alternative free access locations",
+      "items": {
+        "properties": {
+          "evidence": {
+            "description": "How location was determined",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "host_type": {
+            "description": "Host type: publisher, repository, etc.",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "license": {
+            "description": "License type",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "pdf_url": {
+            "description": "Direct PDF URL if available",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "repository": {
+            "description": "Repository institution name",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "url": {
+            "description": "Access URL for full text",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "version": {
+            "description": "Version: published, accepted, submitted",
+            "type": [
+              "string",
+              "null"
+            ]
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "published_date": {
+      "description": "Publication date",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "publisher": {
+      "description": "Publisher name",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "title": {
+      "description": "Paper title",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "year": {
+      "description": "Publication year",
+      "type": [
+        "integer",
+        "null"
+      ]
+    }
+  },
+  "required": [
+    "doi",
+    "doi_url",
+    "title",
+    "genre",
+    "year",
+    "published_date",
+    "publisher",
+    "journal_name",
+    "journal_issns",
+    "journal_is_oa",
+    "journal_in_doaj",
+    "is_oa",
+    "oa_status",
+    "has_repository_copy",
+    "authors",
+    "best_location",
+    "other_locations"
+  ],
+  "type": "object"
+}

First observedMay 11, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive. The description adds the output structure, which aids understanding of tool behavior. No contradictions; behavioral disclosure is sufficient given the annotations.

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 a single, well-structured sentence that front-loads the core action and then lists return fields. No superfluous text; every word adds value.

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

Completeness5/5

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

With an output schema present (implied by context signal), the description does not need to explain return values in depth, but it does so briefly. Full input specification and clear output description make it complete for a 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?

Schema coverage is 100% and includes a description and examples for the DOI parameter. The tool description adds minimal extra meaning beyond the schema, so baseline 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: fetch open-access status and the best free legal copy given a DOI. It specifies the inputs (DOI) and outputs (is_oa, oa_status, best location, journal metadata), distinguishing it from sibling tools like search_papers.

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 explicitly mentions the input (DOI) and what it does, so usage context is clear. However, it does not provide explicit guidance on when not to use it or compare to alternatives, which prevents a perfect score.

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

All Unpaywall tools Inspect

Try in Browser

RayrunBuild, deploy, and operate MCP servers without becoming an infrastructure team.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.