screenshot_diagram

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

With no annotations provided, the description carries the full burden. It discloses that the tool captures the current diagram as it appears in the editor, returns a PNG image, and requires a specific runtime prerequisite (open in VS Code with extension connected). These are useful behavioral details beyond the basic action, though it doesn't cover error cases or exact viewport scope.

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

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

The description is two sentences long and front-loads the core action ('Capture a screenshot'), then explains the purpose and prerequisite. Every sentence earns its place; there is no redundancy or fluff.

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

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

For a simple screenshot tool with three parameters fully described in the schema, the description covers the purpose, output, and prerequisite. It could add more detail about error conditions or what exactly is included in the screenshot (e.g., entire canvas vs. visible area), but it is adequate for selecting and invoking the tool correctly.

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

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

Schema description coverage is 100%, so the parameters are already well-documented (filePath, scale, border). The description adds minimal semantic value beyond the schema, and the baseline 3 is appropriate per the rubric.

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

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

The description opens with a specific verb-resource pairing: 'Capture a screenshot (PNG image) of the current draw.io diagram as it appears in the editor.' It clearly distinguishes the tool from siblings like read_diagram by emphasizing visual layout, styling, and readability, making the purpose unmistakable.

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

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

The description provides clear context for when to use the tool: 'so a vision-capable model can analyze the visual layout, styling, and readability.' It also states a prerequisite: 'Requires the diagram to be open in VS Code with the companion extension connected.' However, it does not explicitly mention alternatives or when not to use it, so it falls short of a 5.

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