Cronometer MCP

set_macro_targets

Idempotent

Update calorie and protein, carb, and fat targets for one day, changing only specified values and keeping the rest unchanged.

Instructions

Change the calorie and macro targets for one day.

Only the values given change; the rest are read first and kept. For a lasting change across the week, use create_macro_template and set_weekly_macro_schedule instead.

Args: date: YYYY-MM-DD (defaults to today). calories: Energy target in kcal. protein_grams: Protein target in grams. carbs_grams: Net carbs target in grams. fat_grams: Fat target in grams. template_name: Label for the day's targets (defaults to "Custom Targets").

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": "set_macro_targets"
  }
}

Input Schema

Name	Required	Description	Default
`date`	No
`calories`	No
`fat_grams`	No
`carbs_grams`	No
`protein_grams`	No
`template_name`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.1.0Nov 14, 2026

TDQS

A4.6/5.0

Behavior4/5

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

Annotations already declare idempotentHint=true, destructiveHint=false and readOnlyHint=false, so the safety profile is known. The description adds genuinely new behavioral context by disclosing partial-update semantics ('Only the values given change; the rest are read first and kept'), which is exactly what an agent needs before mutating a record. It does not mention permission requirements or what happens if calorie and macro values conflict, keeping it at a 4 rather than a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded purpose, then mutation semantics, then the alternative routing, then a compact Args block. Every line is useful, though the Args section is somewhat verbose relative to a six-field tool and could have been tighter.

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 mutation tool with an output schema, the description covers purpose, partial-update behavior, all six parameters and the correct sibling alternatives. It stops short of describing validation behavior or whether the template_name creates a reusable template versus just a label, which is a minor remaining ambiguity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description carries the full burden and does: every one of the six parameters is given meaning, units (kcal, net carbs in grams), format (YYYY-MM-DD) and a default ('defaults to today', 'defaults to "Custom Targets"'). This fully compensates for the undocumented schema.

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 opening sentence names a specific verb (change) and resource (calorie and macro targets) with an explicit scope limit ('for one day'), which immediately separates it from the week-level siblings. An agent can identify the operation without opening the schema.

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

Usage Guidelines5/5

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

It states the alternative explicitly: 'For a lasting change across the week, use create_macro_template and set_weekly_macro_schedule instead.' Combined with the one-day framing, the when-to-use and when-not-to-use conditions are both covered.

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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