Screenshot

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

With no annotations, the description carries the full behavioral burden. It usefully discloses the auto-resize default (maxEdge=1600) and the vision-token rationale, plus the return type. It omits real operational traits such as OS screen-recording permission requirements and what happens with occluded or off-screen windows.

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?

Three tight sentences: what it does, when to use it, then a cost-related default. Purpose is front-loaded and every sentence 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 zero-required-param, single-purpose capture tool with a 100%-documented schema, the description covers purpose, trigger, and the key cost tradeoff; the returned image type is stated so no output schema is needed. It falls just short on permission/OS prerequisites that an agent may need before calling.

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 format, maxEdge, quality, and displayId are already fully documented in the schema, including defaults and ranges. The description's mention of maxEdge=1600 only repeats what the schema default already states, adding no new semantic detail.

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?

States a specific verb+resource ('Capture the entire primary display... return it as an image') and defines scope as the whole display, which implicitly separates it from the sibling screenshot_region. An agent can tell what this returns without opening the schema.

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?

Gives clear when-to-use triggers ('when the user asks you to see, look at, describe, or troubleshoot what's on their screen'). However, it never names the alternative siblings (screenshot_region, screenshot_if_changed, get_screen_diff) or states when NOT to use this, leaving sibling routing to inference.

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