APIVerve

Chart Generator

ChartGenerator

Read-only

Chart Generator: Chart Generator is a chart API that turns your data into chart and graph images. Supports bar, line, pie, doughnut, radar, polar area, scatter and bubble charts with customizable styling. (Cost: 10 credits)

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": {
      "datasets": "<datasets>"
    },
    "name": "ChartGenerator"
  }
}

Input Schema

Name	Required	Description	Default
`type`	No	Chart type	bar
`title`	No	Optional title displayed on the chart
`width`	No	Image width in pixels
`format`	No	Output format	png
`height`	No	Image height in pixels
`labels`	No	Array of labels for the x-axis or chart segments. Required except for scatter and bubble charts, whose points carry their own x values
`options`	No	Chart.js compatible options for scales, legend, and more
`datasets`	Yes	Array of datasets with 'name' and 'values'
`backgroundColor`	No	Canvas background: a colour name, #hex, rgb()/rgba(), or transparent (PNG and SVG only; JPEG falls back to white). Defaults to white	white

Output Schema

Name	Required	Description
`data`	No
`error`	No	Error message, null on success
`status`	No	"ok" on success

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 7, 2026

TDQS

A3.8/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the bar is lower. The description adds a genuinely useful behavioral fact beyond the annotations: each call costs 10 credits, which affects whether an agent invokes it speculatively. It does not describe latency or size limits.

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?

Two compact sentences with capability and cost front-loaded. The opening 'Chart Generator: Chart Generator is a chart API' redundantly repeats the name/title, which is the only notable waste.

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 9-parameter tool with nested datasets and a full output schema, the description covers what is produced (chart images), which chart types are valid, and the credit cost. Return-format details are left to the output schema, which is appropriate. Minor gap: no guidance on dataset/value shape beyond the schema.

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 baseline is 3. The description adds real value over the schema by enumerating the concrete accepted chart types (bar, line, pie, doughnut, radar, polar area, scatter, bubble), whereas the schema's 'type' property only says 'Chart type' with a single 'bar' example. That enumeration meaningfully documents the most important parameter.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource — turning data into chart and graph images — and enumerates supported chart types, which separates it from the many other image-conversion siblings like HTMLtoImage or MarkdowntoImage. It does not explicitly name a sibling alternative, but the purpose is unambiguous.

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 only implied: the agent can infer this is the tool for rendering data as a chart image, but there is no guidance on when to prefer it over other image generators, no prerequisites, and no mention of when a different chart type or output format should be chosen. Read-only and openWorld annotations help the agent reason about side effects.

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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