Flat Earth Science

True size on a Mercator map

compare_true_size

Read-onlyIdempotent

Shows how much a Mercator map distorts a country's area, from its real area and the latitude it is drawn at. Returns the real area, the area multiplier at the country's own latitude and at a chosen latitude, and the size it appears at each. Covers the nine countries and regions in the website's size table.

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": {
      "country": "<country>"
    },
    "name": "compare_true_size"
  }
}

Input Schema

Name	Required	Description	Default
`country`	Yes	Greenland, Alaska, Russia, Canada, United Kingdom, Australia, India, Brazil or Africa.
`latitude`	No	Latitude in degrees to move the country to, north positive: -85 to 85. Defaults to the equator, 0.

Output Schema

Name	Required	Description	Default
`item`	Yes
`view`	Yes
`request`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 11, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already establish read-only, idempotent, closed-world behavior, so the description doesn't need to restate safety. It does add real context beyond them: the computation is deterministic from the country's real area and its drawing latitude, and the tool is restricted to a fixed set of nine countries/regions — a meaningful behavioral limit an agent would otherwise only discover by failing.

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

Conciseness4/5

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

Three front-loaded sentences that cover purpose, output, and scope with no filler. Minor redundancy: the return contents are enumerated in some detail even though an output schema exists, and "the website's size table" is an oddly anchored reference.

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?

With an output schema present, the description needn't document the return shape in detail, and the two parameters are fully described in the schema. What remains adequately covered is the conceptual model (own latitude vs chosen latitude) and the nine-country restriction; only explicit alternative-tool routing is absent.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3, but the description goes further by explaining that `latitude` moves the country and that results are reported both at the country's own latitude and at the chosen one — clarifying the comparison semantics that the schema alone only hints at. The `country` parameter's closed list is already in the schema, so no additional credit there.

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?

"Shows how much a Mercator map distorts a country's area" names a specific verb and a specific quantity, and the mechanism (real area + drawing latitude) makes it unmistakable against siblings like compare_flat_map_distance or calculate_curvature, which deal with distance and curvature rather than area.

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

Usage Guidelines3/5

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

Usage is implied rather than stated: the agent can infer this is the tool for Mercator area distortion, and "Covers the nine countries and regions in the website's size table" gives a useful scope boundary. However, there is no explicit when-to-use/when-not guidance and no routing to any alternative for other countries or other map projections.

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

All Flat Earth Science tools Inspect

Try in Browser

One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.