ourairports-mcp-server

ourairports_list_countries

Read-onlyIdempotent

List the countries present in the bundled OurAirports dataset with their ISO 3166-1 alpha-2 codes and airport counts. This is the lookup table for valid country (and, with include_regions, region) filter values used by ourairports_search_airports. Optionally restrict to a continent or nest each country's regions. Counts exclude closed airports.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`continent`	No	Restrict to one continent: AF (Africa), AN (Antarctica), AS (Asia), EU (Europe), NA (North America), OC (Oceania), SA (South America).
`include_regions`	No	When true, nest each country's ISO 3166-2 regions (with airport counts) under it. Off by default to keep the response compact.

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`notice`	No	Guidance when the continent filter matched no countries.
`countries`	No	Countries present in the dataset, sorted by name.
`totalCount`	No	Number of countries returned.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 19, 2026
- removedOutput schema / properties / countries / items / properties / continent / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / countries / items / properties / continent / type
```
Added value: +[
+  "string",
+  "null"
+]
```

Changed6 schema fields changedAug 25, 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": [
+      "countries",
+      "totalCount"
+    ]
+  },
+  {
+    "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: -[
-  "countries",
-  "totalCount"
-]

First observedJun 16, 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=true and idempotentHint=true, so the safety profile is covered. The description adds valuable behavioral details beyond annotations: counts exclude closed airports, the data is from a bundled dataset, and include_regions defaults to false to keep output compact. These specifics deepen transparency without contradicting 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 with no wasted words. The primary purpose is front-loaded, and the usage pointer to ourairports_search_airports appears early. Behavioral notes are compact and placed after the main purpose, preserving clear structure.

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?

The tool has only two optional parameters and an output schema, so the description does not need to explain return values. It covers the core purpose, when to use it, and relevant behavioral nuances (closed-airport exclusion, default behavior). Everything an agent needs to understand before invoking the tool is present.

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 description coverage is 100%, so both parameters (continent, include_regions) are already well-documented in the schema. The description repeats the existence of these parameters and adds a small rationale for the default of include_regions (compact response). This adds marginal value but does not substantially extend the schema's meaning, so a baseline 3 is appropriate.

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 states a specific verb (List), a clear resource (countries in the bundled OurAirports dataset), and specific output details (ISO codes, airport counts). It also distinguishes itself from siblings by identifying the tool as the lookup table for valid country/region filter values used by ourairports_search_airports.

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 clearly conveys when to use this tool: to obtain valid country (and optionally region) filter values for ourairports_search_airports. It also mentions optional continent restriction and region nesting, which defines use cases. It does not explicitly list when-not-to-use or name alternative sibling tools, but the guidance is clear enough without them.

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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