ChartAnt

Small multiples

generate_small_multiples

Read-only

Draw the same small chart once per group (country, product, team) in a grid, all on one shared scale, so the groups can be compared at a glance. Rows are {group, x, value}, e.g. {group:'France', x:'Jan', value:120}. Up to 24 groups.

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": {
      "data": "<data>"
    },
    "name": "generate_small_multiples"
  }
}

Input Schema

Name	Required	Description
`data`	Yes
`unit`	No	Unit for the legend, e.g. 'EUR', 'users', '%'.
`chart`	No	Default line.
`title`	No	Title shown above the map.
`columns`	No
`brandTheme`	No	Name of a brand theme saved on the user's account (their colours and footer), only when the user asks for their theme. Or "colorblind" for colours that people with colour-vision deficiency can tell apart (anyone can use it).

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 14, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations only declare readOnlyHint=true; the description adds real behavioral context beyond that - all panels share one scale, and there is a hard cap of 24 groups that the input schema does not enforce. It does not say what is produced (image, spec, or URL), which is the main remaining gap.

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?

Three short sentences ordered purpose, data format, then limit - front-loaded and free of filler. The inline example earns its space by clarifying the required row structure.

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?

Covers the data contract and the group limit, which are the two things an agent could get wrong; with no output schema, the return format is the one unaddressed element, though for a chart generator that is largely predictable.

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?

The row shape {group, x, value} with a worked example (France/Jan/120) gives meaning the schema lacks, since those properties carry no descriptions there. With 67% schema coverage and rich schema text for brandTheme, unit, and chart, the description's partial coverage is acceptable but leaves columns and title unaddressed.

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 and resource - draw the same small chart once per group in a grid on a shared scale - which is exactly what separates it from single-chart siblings like generate_line_chart or generate_column_chart. The parenthetical examples (country, product, team) make the intended resource concrete.

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

Usage Guidelines3/5

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

Usage is implied rather than stated: the phrase 'so the groups can be compared at a glance' signals the comparison use case, and 'Up to 24 groups' bounds it, but there is no explicit when-to-use/when-not guidance or named alternative such as a single grouped bar chart.

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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