Take a screenshot

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, and the description reinforces this with 'Read-only.' Beyond that it discloses the return shape (a line with the size) and a key behavioral fact: pixel coordinates in the image map exactly to the ones amiga_mouse, amiga_drag and amiga_input consume. It does not describe the image encoding/attachment mechanics or clipping behavior for off-screen windows, which keeps it below a 5.

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?

Front-loaded with the core action, then scoping options, then the coordinate-frame contract, then routing to alternatives. No filler sentences; every clause carries information an agent needs.

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?

With no output schema, the description must carry return-value information, and it does partially by mentioning the accompanying size line; the PNG payload itself is implied. For a 2-optional-parameter read tool with full annotation coverage this is nearly complete, missing only edge-case behavior (e.g., what happens if a window title matches multiple windows).

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% and both parameters are described there (region as a nested object with x/y/width/height, window as a partial title match), so baseline is 3. The description earns above baseline by establishing that region coordinates share the coordinate system of the pointer/input tools and that window/region capture is cheaper than full-screen.

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 and resource ('Capture the front screen as a PNG image') plus its three scoping variants (full screen, one window, a rectangle). It is immediately distinguishable from amiga_windows, amiga_ui_list and amiga_region_changed, which it names.

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 explicit when-to-use guidance ('see the screen before clicking') plus two named alternatives with the conditions that select them: amiga_ui_list for finding buttons by name (cheaper) and amiga_region_changed for change detection only. Includes the tradeoff rationale (window/region is smaller and faster).

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