Calcgrid

Circle Calculator

calculate_circle_properties

Read-onlyIdempotent

Use this when you know a circle's radius or diameter and need its area, circumference or the other dimension. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery.

Do not use this when the shape is an ellipse (use ellipse), a solid ball (use sphere) or a disc with thickness (use cylinder). What it computes: Computes the area, circumference, diameter and radius of a circle from either its radius or its diameter. Lengths are unit-agnostic: the area is in the square of the input unit. Example user requests: Calculate the area and circumference of a circle with radius 3. | A circle has diameter 10; return its radius, circumference and area. Inputs: radius (number, units, optional); diameter (number, units, optional). Valid input combinations: Provide at least one of radius or diameter. You may provide both when diameter equals 2 × radius; conflicting values are rejected. Complete JSON argument examples: {"radius":3} | {"diameter":10} Outputs: radius [units], diameter [units], circumference [units], area [units²]. Formula: r = radius (or diameter / 2); diameter = 2·r; circumference = 2·π·r; area = π·r² Direct REST fallback: POST https://tttkmbb.com/api/v1/calculate/circle with the same JSON input fields. Do not guess another /api/* path. Docs: https://tttkmbb.com/geometry/circle.md

Input Schema

TableJSON Schema

Name	Required	Description	Default
`radius`	No	Radius of the circle. Give either radius or diameter. Unit: units.
`diameter`	No	Diameter of the circle (2 × radius). Used when radius is not given. Unit: units.

Output Schema

TableJSON Schema

Name	Required	Description
`links`	No
`result`	Yes
`request`	Yes
`sources`	No
`success`	Yes
`version`	No
`freshness`	No
`timestamp`	Yes
`next_actions`	No
`service_version`	Yes	Deployed Calcgrid implementation version used for the result.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 27, 2026

addedOutput schema / properties / service_version

Added value: +{
+  "description": "Deployed Calcgrid implementation version used for the result.",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "success",
-  "request",
-  "result",
-  "timestamp"
-]New value: +[
+  "success",
+  "service_version",
+  "request",
+  "result",
+  "timestamp"
+]

Changed3 schema fields changedSep 26, 2026

addedInput schema / anyOf

Added value: +[
+  {
+    "required": [
+      "radius"
+    ]
+  },
+  {
+    "required": [
+      "diameter"
+    ]
+  }
+]

addedInput schema / description

Added value: +"Provide at least one of radius or diameter. You may provide both when diameter equals 2 × radius; conflicting values are rejected."

addedInput schema / examples

Added value: +[
+  {
+    "radius": 3
+  },
+  {
+    "diameter": 10
+  }
+]

AddedSep 25, 2026
RemovedSep 25, 2026
First observedSep 25, 2026

TDQS

A4.7/5.0

Behavior4/5

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

Annotations already indicate the tool is read-only and idempotent, and the description adds meaningful behavioral context: it is unit-agnostic, rejects conflicting radius/diameter values, and returns all four properties from either input. There is no contradiction between the description and the annotations, and the additional constraints help the agent understand expected behavior.

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 longer than average but every section earns its place: usage, exclusions, computed outputs, example inputs, valid combinations, JSON examples, formulas, and REST fallback. It is clearly structured with labeled sections, and the most important usage guidance is front-loaded. This is an appropriate level of detail for guiding an agent.

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 straightforward geometry calculator, the description covers everything needed to call it correctly: input semantics, valid combinations, output properties, formulas, and complete JSON examples. The presence of an output schema and annotations further reduces the need to explain return structure or side effects. Nothing essential is missing.

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?

The input schema already documents both parameters with units and examples, so the baseline is 3. The description adds extra meaning by explaining valid input combinations, the requirement that diameter must equal 2 × radius when both are provided, and the exact formulas used. This goes beyond the schema by clarifying the relationship and constraints between the parameters.

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 names a specific verb and resource: it computes area, circumference, diameter, and radius of a circle from radius or diameter. It clearly distinguishes this from sibling shape calculators by explicitly excluding ellipses, spheres, and cylinders. This leaves no ambiguity about what the tool does.

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?

The description explicitly states when to use the tool ('when you know a circle's radius or diameter and need its area, circumference or the other dimension'), when not to use it, and names the alternative tools for ellipse, sphere, and cylinder. It also instructs the agent to call the tool directly rather than computing from memory, providing clear behavioral guidance.

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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