Nightscout MCP Server

weekly_comparison

Compare this week's glucose metrics to last week's automatically, revealing TIR, average, CV, HbA1c, and time-in-ranges with improvement indicators. No parameters required.

Instructions

One-call comparison of this week vs last week. Automatically calculates both periods and returns side-by-side stats: TIR, average, CV, HbA1c, time-in-ranges with improvement indicators. No parameters needed.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "weekly_comparison"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.4.0Sep 6, 2026

TDQS

A4.2/5.0

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 that the tool automatically calculates both periods and returns improvement indicators, which is useful. However, it does not mention that the operation is read-only, whether historical data is required, or how incomplete weeks are handled. These are notable gaps but not misleading omissions.

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 two sentences with zero filler. The core purpose is front-loaded in the first sentence, followed by the concrete output list and a note about parameters. Every piece of text earns its place.

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 zero-parameter tool, the description is quite complete: it names the output fields, improvement indicators, and the automatic period calculation. The absence of an output schema is compensated by listing the stats. It could be improved by noting prerequisites like data availability for the previous week, but overall it provides sufficient context for an agent to call it 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?

There are zero parameters, and the input schema has no properties, so the description's statement 'No parameters needed' accurately reflects and reinforces the schema. Per the rubric, a zero-parameter tool receives a baseline of 4, and the description adds no unnecessary parameter detail.

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's function with a specific scope: comparison of this week vs last week, followed by the exact stats returned (TIR, average, CV, HbA1c, time-in-ranges). It distinguishes itself from sibling tools like compare_periods by emphasizing no parameters and an automated, fixed period calculation.

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 implies when to use the tool: when a week-over-week comparison is needed in one call, with 'No parameters needed' signaling a zero-config shortcut. It provides clear context but does not explicitly name alternatives or state exclusions such as custom date ranges, which would route agents to compare_periods.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.