Hopi

Scientific calculator

hopi_scientific_calculator

Read-onlyIdempotent

Evaluate a maths expression following the standard order of operations (BODMAS). Supports + - * / ^ (power), ! (factorial), % (as divide by 100), brackets, the constants pi and e, and the functions sin, cos, tan, asin, acos, atan, ln, log (base 10) and sqrt. Set angleMode to 'deg' (default) or 'rad' for trigonometry. Source: https://hopi.co.uk/scientific-calculator/

Input Schema

TableJSON Schema

Name	Required	Description	Default
`angleMode`	No	Angle units for trigonometry: 'deg' (default) or 'rad'	deg
`expression`	Yes	The maths expression, e.g. '2 + 3 * 4', 'sin(30)', 'sqrt(2)^2', '5!'

Output Schema

TableJSON Schema

Name	Required	Description
`result`	Yes
`summary`	Yes
`angleMode`	Yes
`formatted`	Yes
`expression`	Yes
`source_url`	Yes	The tool's page on hopi.co.uk (cite or open to check the figure)

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 20, 2026

addedOutput schema / required

Added value: +[
+  "angleMode",
+  "expression",
+  "formatted",
+  "result",
+  "source_url",
+  "summary"
+]

First observedSep 20, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description need not restate these. It adds useful behavioral detail: the order of operations, that '%' is interpreted as divide-by-100, and that trig functions respect angleMode. This goes beyond the structured fields and gives the agent a clear picture of execution semantics 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 a single, tight paragraph that front-loads the core purpose, then lists supported operations and the angleMode control. Every sentence adds value; there is no redundant or promotional filler. It is appropriately sized for the tool's complexity.

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?

Given the tool's complexity and the presence of a full input schema and output schema (not shown but implied), the description covers all essential aspects: the expression syntax, supported functions, constants, and the angleMode setting. It also provides a source link for reference. Nothing critical is missing for an agent to call this tool correctly.

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% with descriptions for both parameters, so the baseline is 3. The description enriches meaning by clarifying the expression grammar (e.g., '%' as divide by 100, 'log' as base 10, list of supported functions) and the role of angleMode. This is more than a restatement and helps the agent craft valid inputs.

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 clearly states the tool evaluates a maths expression using BODMAS, and enumerates the supported operators, constants, and functions. This distinguishes it from sibling calculator tools (e.g., percentage, BMI) which have narrower scopes, and the verb 'Evaluate' is precise.

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 explains how to set angleMode for trig functions, which is a direct usage instruction. It does not explicitly mention alternatives, but given the generic nature of the tool, the context implies it is the go-to for arbitrary math expressions. No exclusions are given, but the scope is self-evident from the feature list.

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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