MCP Screenshot Server

add_box

Draw a rectangle on an image by specifying its top-left coordinates, width, height, color, fill, and line width to annotate screenshots.

Instructions

Draw a rectangle/box on the image.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`x`	Yes	X coordinate of the top-left corner
`y`	Yes	Y coordinate of the top-left corner
`fill`	No	Fill color (None for no fill)
`color`	No	Color of the box (e.g., 'red', '#FF0000')	red
`width`	Yes	Width of the box
`height`	Yes	Height of the box
`image_id`	Yes	ID of the image to annotate
`line_width`	No	Width of the box outline

Output Schema

TableJSON Schema

Name	Required	Description	Default
`message`	Yes	Status message
`image_id`	Yes	Image ID that was annotated

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 15, 2026

TDQS

B3.4/5.0

Behavior2/5

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

No annotations are provided, so the description must carry the behavioral burden. It only restates that a box is drawn and does not disclose side effects on the image, whether the change is reversible, or what the tool returns beyond the available output schema.

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?

A single, front-loaded sentence that states exactly what the tool does with no filler or redundancy.

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?

The tool is a simple drawing operation, and the input schema fully documents all parameters while an output schema exists. The description could add behavioral notes, but the overall context is reasonably complete for an agent to invoke the tool correctly.

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

Parameters3/5

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

Schema description coverage is 100%, so all 8 parameters are already documented. The description itself adds no parameter-level semantics, which is acceptable because the schema carries that weight.

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 clearly states the action ('draw') and the target object ('rectangle/box on the image'). It is easy to tell apart from sibling tools like add_circle, but it does not explicitly name those alternatives.

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?

The wording implies when to use the tool: whenever a rectangular box is needed. There are no explicit when-to-use or when-not-to-use conditions, and no alternatives are mentioned, but the simple domain makes the intended use fairly evident.

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