test_dark_mode

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

No annotations are provided, so the description carries full burden. It discloses key behaviors (persistence, screenshot return) but lacks details about potential side effects, limitations, or required browser support. For a simple emulation tool, the disclosure is adequate but not comprehensive.

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?

Two sentences with zero waste. The first sentence states the action and output, the second provides usage context and persistence. Every word earns its place.

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 tool with two parameters and no output schema, the description covers the essential details: purpose, return value, and persistence. However, it omits specifics about the screenshot format (e.g., base64, file) and potential limitations. Still, it is sufficiently complete for typical use.

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 coverage is 100% with descriptions for both parameters (mode enum, session_id). The description adds context by stating 'on a session' and explaining the mode purpose, but does not add significant new information beyond what the schema already provides.

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 uses specific verbs ('Emulate' and 'screenshot') and clearly identifies the resource ('prefers-color-scheme (dark or light)'). It distinguishes this tool from siblings like set_viewport or check_color_contrast by specifying the exact color scheme emulation.

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 explicitly states when to use the tool ('to verify a site's dark/light theming without touching OS settings') and notes that emulation persists for later actions. It implies context but does not explicitly mention when not to use it or alternatives.

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