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

Goes beyond the annotations by disclosing that the operation overwrites the entire Edge.Cuts layer and that the three inputs are mutually exclusive, which the annotations (readOnlyHint=false, destructiveHint=false) do not convey. There is mild tension between 'Replace everything' and destructiveHint=false, and no statement about reversibility or permissions, so it is not 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?

A single front-loaded sentence with the verb first, three compact parentheticals, and a closing constraint followed by a short imperative. Dense but every clause earns its place; no filler.

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 6-parameter, nested-object mutation with no output schema, it covers the mode selection and the exactly-one rule well enough for an agent to call it. The main gap is line_width_mm, which is explained nowhere, so the definition is not fully complete.

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?

With schema coverage at 33%, the description carries real weight: it explains what rect, corner_radius_mm, polygon-as-points, and fit_to_parts/margin_mm mean, which the flattened schema leaves thin. It never mentions line_width_mm (undocumented anywhere) or design_id, leaving a gap.

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 ('Replace everything on Edge.Cuts with a new outline') and enumerates the three outline modes, which cleanly separates it from siblings like set_zones/set_keepouts that also write geometry. It stops short of naming a sibling, so it is clear but not maximally disambiguated.

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 an explicit, load-bearing usage rule: 'Give exactly one' of rect/polygon/fit_to_parts. It also implicitly tells the agent which mode to pick by describing each (rectangle, point polygon, auto-fit around courtyards). It does not state prerequisites or when to avoid this tool vs. alternatives, 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.