ChartAnt

US county map

generate_county_map

Read-only

Draw a map of US counties coloured by a number: all of the US, or the counties of one state. Name counties with their state ("Cook, IL", "Los Angeles County, California") or use 5-digit FIPS codes ("17031"). With 'state' set, bare county names are looked up in that state. For states, use generate_country_map with country 'US'.

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_county_map"
  }
}

Input Schema

Name	Required	Description
`data`	Yes	One row per county.
`unit`	No	Unit for the legend, e.g. 'EUR', 'users', '%'.
`state`	No	Only this state, e.g. 'TX' or 'Texas'. Leave out for the whole US.
`title`	No	Title shown above the map.
`width`	No	Image width in pixels (default 960).
`format`	No	png (default) or svg. SVG returns a link to a vector version of the map.
`height`	No	Image height in pixels (default 600).
`labels`	No	Write each area's name, value or both on the map (default none). Labels that don't fit are left out.
`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

Behavior3/5

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

Annotations already declare readOnlyHint=true, so the safe-read profile is covered. The description adds the naming-resolution behavior and FIPS fallback, which is useful context, but says nothing about what the tool returns (image vs. link), rate limits, or failure behavior when a county cannot be matched.

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?

Four tight sentences with the scope constraint front-loaded and the sibling routing placed at the end where it belongs. The quoted examples are justified by real format ambiguity rather than padding.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a chart-generation tool with nine well-documented parameters and no output schema, the description covers the operation, scope, identifier formats, and the correct sibling for the state-level case. The only minor omission is the return shape, which is largely implied by 'Draw a map'.

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?

Schema coverage is 100%, so the baseline is 3, but the description goes further for the least-documented field: the 'county' item has no schema description, and the description supplies accepted formats with concrete examples ("Cook, IL", "Los Angeles County, California", "17031") plus the state-scoped bare-name rule. Other parameters like width, labels, and brandTheme are left to the 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?

States a specific verb and resource with scope: "Draw a map of US counties coloured by a number", and immediately bounds the scope to all US or one state. It also names the sibling tool to use instead for states, so an agent can distinguish it from generate_country_map without opening either schema.

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?

Gives an explicit routing rule — use generate_country_map with country 'US' for states — and explains that bare county names are resolved against the 'state' parameter when set. It does not describe any other alternative or exclusion, but the boundary that matters most is stated plainly.

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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