API Tool Calls

BMI Calculator

bmi_calculator

Read-onlyIdempotent

Calculate adult BMI and its band from weight, height and units.

Example tool call

This call uses example arguments supplied in the tool’s input schema.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "height": 1.75,
      "weight": 70
    },
    "name": "bmi_calculator"
  }
}

Input Schema

Name	Required	Description	Default
`units`	No		metric
`height`	Yes	Metres (metric) or total inches (imperial)
`weight`	Yes	Kilograms (metric) or pounds (imperial)

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

AddedOct 4, 2026

TDQS

A3.6/5.0

Behavior3/5

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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds that output includes the classification band and that the calculation targets adults, but discloses no further behavioral traits (e.g. edge cases).

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?

A single front-loaded sentence with zero filler. Every clause earns its place by naming the action, output, and inputs.

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?

An output schema exists, so return values need no explanation, and annotations cover the safety profile. For a deterministic calculator the description covers essentials, though it omits unit-mismatch or range caveats.

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 coverage is 67% and both height and weight carry unit-interpretation descriptions, while units is a self-documenting enum with a default. The description merely names the three inputs and adds no meaning beyond the schema, 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 verb (Calculate) and resource (adult BMI and its band) with clear inputs (weight, height, units). The 'adult' qualifier usefully scopes it and separates it from siblings like body_fat_calculator without ambiguity.

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

Usage Guidelines2/5

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

No when-to-use, when-not, or alternative-tool guidance is given. With related siblings such as body_fat_calculator and one_rep_max_calculator present, the description offers nothing to route an agent between them.

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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