MapMap

geo_distance

Distance in metres between two coordinates. Computed geodesically on the WGS84 ellipsoid, so it is the straight-line (as-the-crow-flies) distance, NOT a driving distance, use route or matrix for travel distance and time. Local computation: no network call, no quota.

Input Schema

Name	Required	Description	Default
`to`	Yes	End coordinate.
`from`	Yes	Start coordinate.

Output Schema

Name	Required	Description	Default
`distance_m`	Yes	Distance in metres along the WGS84 ellipsoid.

Schema Changelog

Changes observed during successful MCP inspections.

Changed5 schema fields changedSep 23, 2026

addedInput schema / $defs / LatLon / anyOf

Added value: +[
+  {
+    "properties": {
+      "lat": {
+        "description": "Latitude in decimal degrees (−90 to 90).",
+        "format": "double",
+        "type": "number"
+      },
+      "lon": {
+        "description": "Longitude in decimal degrees (−180 to 180).",
+        "format": "double",
+        "type": "number"
+      }
+    },
+    "required": [
+      "lat",
+      "lon"
+    ],
+    "type": "object"
+  },
+  {
+    "description": "GeoJSON position [lon, lat]: longitude FIRST.",
+    "items": {
+      "format": "double",
+      "type": "number"
+    },
+    "maxItems": 2,
+    "minItems": 2,
+    "type": "array"
+  }
+]

changedInput schema / $defs / LatLon / description

Previous value: -"A WGS84 coordinate pair in decimal degrees."New value: +"A WGS84 coordinate in decimal degrees: a {lat, lon} object (preferred), or a GeoJSON [lon, lat] array with LONGITUDE FIRST, the same order as every polygon field on this server."

removedInput schema / $defs / LatLon / properties

Removed value: -{
-  "lat": {
-    "description": "Latitude in decimal degrees (−90 to 90).",
-    "format": "double",
-    "type": "number"
-  },
-  "lon": {
-    "description": "Longitude in decimal degrees (−180 to 180).",
-    "format": "double",
-    "type": "number"
-  }
-}

removedInput schema / $defs / LatLon / required
```
Removed value: -[
-  "lat",
-  "lon"
-]
```
removedInput schema / $defs / LatLon / type
```
Removed value: -"object"
```

First observedSep 1, 2026

TDQS

A4.5/5.0

Behavior4/5

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

No annotations are provided, so the description carries the full burden, and it delivers the two facts an agent most needs: the computation is local with no network call and no quota, and the result is geodesic rather than routed. It does not discuss precision, edge cases (antipodal points), or units of the return value, but the output schema covers the return shape.

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?

Three short sentences, front-loaded with the core definition, then the disambiguation, then the operational caveat. Every sentence carries distinct information and none is filler.

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?

For a two-parameter pure-computation tool with a full output schema, the description covers purpose, unit, semantics, sibling routing, and cost profile. Nothing an agent needs to invoke it correctly is missing.

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% and the nested LatLon definition thoroughly documents the coordinate formats, including the longitude-first GeoJSON array ordering. The description only says 'two coordinates' and adds no semantics beyond what the schema already provides, so the 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?

States a specific resource (distance in metres between two coordinates) and immediately scopes it as geodesic straight-line distance on WGS84. It explicitly names the sibling tools that do something different (`route`, `matrix`), so an agent can distinguish it without opening a schema.

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

Usage Guidelines5/5

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

Gives both sides of the routing decision: use this for as-the-crow-flies distance, use `route` or `matrix` for travel distance and time. The condition that selects this tool versus the alternatives is stated directly rather than implied.

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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