openalex-mcp-server

Openalex Describe Fields

openalex_describe_fields

Read-onlyIdempotent

List valid field names for an OpenAlex entity type and context (filter, group_by, or select). Use proactively before constructing a filter or group_by to avoid invalid-field 400 errors. Pass query to rank the list by name similarity — useful when you have a partial or guessed field name. Ranking never drops a field: the full list comes back either way.

Input Schema

TableJSON Schema

Name	Required	Description
`query`	No	Optional partial or guessed field name to sort results by similarity. Pass the field you tried (e.g. "funder") to get the closest matches first. The complete field list is returned either way — a query reorders it, it does not filter it, so a nested value's parent object (e.g. `summary_stats` for "h_index") is still reachable further down.
`context`	Yes	Field usage context. "filter": fields accepted in the filter param. "group_by": fields accepted in group_by — a subset of the filter set that leaves out what OpenAlex refuses to aggregate (raw dates, *.search operators, decimal scores, display_name, and external-ID fields among them). "select": fields accepted in select.
`entity_type`	Yes	OpenAlex entity type to list fields for.

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`total`	No	Total number of valid fields for this entity_type + context.
`fields`	No	Every valid field name for this entity_type + context — the complete pool, ranked by similarity when `query` is provided. Never truncated, so this always holds `total` entries.
`context`	No	Context queried (filter, group_by, or select).
`entity_type`	No	Entity type queried.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 24, 2026

changedInput schema / properties / context / description

Previous value: -"Field usage context. \"filter\": fields accepted in the filter param. \"group_by\": fields accepted in group_by — a subset of the filter set (raw date and *.search fields are excluded; they cannot be grouped). \"select\": fields accepted in select."New value: +"Field usage context. \"filter\": fields accepted in the filter param. \"group_by\": fields accepted in group_by — a subset of the filter set that leaves out what OpenAlex refuses to aggregate (raw dates, *.search operators, decimal scores, display_name, and external-ID fields among them). \"select\": fields accepted in select."

Changed2 schema fields changedSep 9, 2026

changedInput schema / properties / query / description

Previous value: -"Optional partial or guessed field name to rank results by similarity. Pass the field you tried (e.g. \"funder\") to get the closest matches first. Omit to return all fields for the entity_type + context."New value: +"Optional partial or guessed field name to sort results by similarity. Pass the field you tried (e.g. \"funder\") to get the closest matches first. The complete field list is returned either way — a query reorders it, it does not filter it, so a nested value's parent object (e.g. `summary_stats` for \"h_index\") is still reachable further down."

changedOutput schema / properties / fields / description

Previous value: -"Valid field names, ranked by similarity to query when provided."New value: +"Every valid field name for this entity_type + context — the complete pool, ranked by similarity when `query` is provided. Never truncated, so this always holds `total` entries."

Changed6 schema fields changedAug 22, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "entity_type",
+      "context",
+      "fields",
+      "total"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode.",
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "entity_type",
-  "context",
-  "fields",
-  "total"
-]

Changed1 schema field changedJul 10, 2026

changedInput schema / properties / context / description

Previous value: -"Field usage context. \"filter\": fields accepted in the filter param. \"group_by\": fields accepted in group_by (same valid set as filter). \"select\": fields accepted in select."New value: +"Field usage context. \"filter\": fields accepted in the filter param. \"group_by\": fields accepted in group_by — a subset of the filter set (raw date and *.search fields are excluded; they cannot be grouped). \"select\": fields accepted in select."

AddedJun 8, 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 and idempotentHint. The description adds useful behavioral nuance beyond these: 'Ranking never drops a field: the full list comes back either way,' clarifying that the query parameter only reorders results. This is helpful context not captured in structured fields. No contradiction with 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 three sentences, each with a distinct purpose: state the main action, give the proactive use case, and explain the query behavior. It is front-loaded with the verb and resource, and every sentence earns its place without redundancy or fluff.

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?

Given that an output schema exists, the description does not need to detail return values. It covers the purpose, when to use it, and the notable query ranking behavior. Parameter details and entity/context enumerations are fully handled by the schema. The description is complete for correct agent invocation.

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 input schema has 100% description coverage, with detailed explanations for all three parameters (query, context, entity_type). The description itself adds no further parameter-level meaning, so it does not need to compensate. Baseline of 3 is appropriate because the schema carries the semantic weight.

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 opens with a specific verb and resource: 'List valid field names for an OpenAlex entity type and context (filter, group_by, or select).' The tool's operation is unmistakable and clearly distinct from the siblings (analyze_trends, get_citation_graph, resolve_name, search_entities), which perform different functions.

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 gives explicit usage context: 'Use proactively before constructing a filter or group_by to avoid invalid-field 400 errors.' This tells the agent when to invoke the tool, but it does not explicitly mention alternatives or when not to use it. The sibling names themselves make the distinction obvious, so a small deduction is warranted.

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

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