Flat Earth Science

Horizon distance

get_horizon_distance

Read-onlyIdempotent

Gives the distance to the horizon from an eye height above a smooth sphere, and how far a taller object such as a mast stays in straight sight. Returns the observer's horizon distance, the range added by the target height and the maximum shared sightline.

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": {
      "eyeHeight": "<eyeHeight>"
    },
    "name": "get_horizon_distance"
  }
}

Input Schema

Name	Required	Description
`units`	No	Metric uses kilometres and metres; imperial uses miles and feet. Metric without it.
`eyeHeight`	Yes	Height of the observer's eye above the water or ground: 0.1 to 1000 m, or feet when units is imperial.
`targetHeight`	No	Height of the taller object's top above the same surface: 0 to 1000 m, or feet when units is imperial. Defaults to 10 m (32.8 ft).

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

A3.7/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so safety and determinism are covered. The description adds genuine behavioral context beyond that: the computation assumes a smooth sphere and yields three distinct quantities, including the shared sightline, which tells the agent what model is being applied.

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?

Two tightly packed sentences with no filler, front-loading the core computation before listing the returned quantities. Slightly dense wording ('stays in straight sight') costs a bit of immediate clarity but nothing is wasted.

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 explain return values, and it does briefly name them anyway. Annotations cover safety and idempotency, and the sphere assumption plus the role of the optional target height make this sufficient to call correctly; only explicit sibling routing 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%, so units, eyeHeight and targetHeight are already fully documented with ranges and unit semantics. The description reinforces the targetHeight concept ('how far a taller object such as a mast stays in straight sight') but adds no format or default details beyond the schema; baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('Gives the distance to the horizon from an eye height') and enumerates all three outputs (observer horizon, added range from target height, maximum shared sightline). It doesn't explicitly differentiate itself from siblings like calculate_curvature or get_flight_distance, but the geometry it computes is unambiguous.

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 by the physical setup described ('eye height above a smooth sphere', 'a taller object such as a mast'), and the targetHeight parameter hints at the two-object sightline case. There is no explicit when-to-use statement, no exclusions, and no naming of alternative tools for related curvature or distance questions.

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.