SmartTools

Hours calculator

hours_calculator

Time worked between two clock times (handles overnight), minus a break, with optional pay. Times as HH:MM. Runs on smart-tools.xyz.

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": {
      "start": "<start>",
      "end": "<end>"
    },
    "name": "hours_calculator"
  }
}

Input Schema

Name	Required	Description
`end`	Yes	End time HH:MM (24h)
`start`	Yes	Start time HH:MM (24h)
`locale`	No	Language for the source_url link (default en)
`hourly_rate`	No	Optional pay rate per hour
`break_minutes`	No	Unpaid break in minutes (default 0)

Schema Changelog

Changes observed during successful MCP inspections.

First observedAug 17, 2026

TDQS

A4/5.0

Behavior3/5

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

With no annotations, the description carries the full burden. It discloses key behaviors (overnight handling, break subtraction, optional pay) but does not mention output format, edge cases, or limitations. Some useful context is provided, but gaps remain.

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 extremely concise, front-loading the core purpose in the first sentence. The additional sentence about time format is useful, though 'Runs on smart-tools.xyz' is minor noise. No wasted words.

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?

For a simple calculator with no output schema, the description adequately covers the main computation aspects. It omits details about the response format and locale parameter, but these are either inferable or documented in the schema. Overall, it is sufficiently complete.

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 baseline is 3. The description reinforces 'times as HH:MM' and clarifies 'minus a break' and 'optional pay,' which adds slight meaning beyond schema but does not fully compensate for the undocumented locale parameter.

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 calculates time worked between two clock times, with specific features: handling overnight, subtracting a break, and optional pay. This distinguishes it from sibling tools like time_converter or date_difference_calculator.

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 provides clear context: it is for computing worked hours between clock times, including overnight spans and breaks. It doesn't explicitly exclude alternatives, but the context implies when this tool is appropriate.

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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