List screens

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

Annotations already declare readOnlyHint and idempotentHint, so the description doesn't need to restate them. It adds behavioral detail about coordinate frames (excludes/includes menu bar and Dock), which helps the agent interpret results correctly. Minor gap: no explicit mention of return format, but the frame explanation mitigates this.

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 pack purpose, frame semantics, and usage guidance without redundancy. Every word earns its place, and the structure front-loads the main action clearly.

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 no-parameter list tool, the description covers what it does, the key output distinction (frame vs fullFrame), and how to apply the result. No output schema exists, but the description sufficiently explains the meaningful data, making it complete for the agent's needs.

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?

Tool has zero parameters, so the baseline is 4. The description adds no parameter-specific info because none exist, but it does explain output semantics that relate to how the tool would be used, which indirectly supports parameter understanding for downstream calls.

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?

Description clearly states 'List connected screens' with specific verb and resource, and distinguishes from siblings like hs_list_windows by focusing on screens and coordinate frames. The mention of 'frame' and 'fullFrame' adds precision beyond the title.

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?

Explicitly states a use case: 'Use these bounds when computing arguments for hs_move_window.' This gives clear context for when to use the tool. It doesn't name alternatives, but the tool is unique among siblings for screen listing, so exclusions are less necessary.

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