MCP Utility Tools

date_calculator

Calculate date differences, or add and subtract days from a given date. Provides precise results using YYYY-MM-DD format.

Instructions

Calculate the difference between two dates, or add/subtract days from a date.

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": {
      "operation": "<operation>",
      "date1": "<date1>"
    },
    "name": "date_calculator"
  }
}

Input Schema

Name	Required	Description
`days`	No	Number of days to add or subtract. Required for "add" or "subtract".
`date1`	Yes	The starting date, in YYYY-MM-DD format.
`date2`	No	The second date, in YYYY-MM-DD format. Required for "difference".
`operation`	Yes	One of "difference", "add", or "subtract".

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 11, 2026

TDQS

A4/5.0

Behavior3/5

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

With no annotations provided, the description carries the burden of behavioral disclosure. It states the high-level operations but lacks details on edge cases, error handling, or return format. The existence of an output schema helps, but the description adds minimal behavioral context beyond the basic operations.

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, front-loaded sentence that communicates both primary operations without any filler. It is maximally concise while remaining informative, earning full marks for efficiency.

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 calculation utility, the description plus schema and output schema cover the essential information needed to select and invoke the tool. It could slightly improve by explicitly noting parameter dependencies (e.g., days required for add/subtract), but the schema already communicates these, so the context is nearly 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 coverage is 100%, with each parameter already well-described (e.g., date1 as 'starting date', date2 as 'second date', operation listing allowed values). The description essentially paraphrases the schema without adding new semantic details, so it stays at the baseline of 3.

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 identifies the tool's purpose: calculating date differences or adding/subtracting days. It uses a specific verb and resource, and is well-distinguished from sibling tools like convert_units and hash_text, which serve entirely different functions.

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 states the main use cases ('difference between two dates, or add/subtract days') but does not explicitly mention when not to use the tool or compare it to alternatives. However, since all sibling tools are unrelated utilities, the context is clear enough, earning a 4 rather than a 5.

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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