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

Annotations already declare a non-read-only, non-destructive, closed-world mutation, and the description adds real value on outcomes: nothing is left outside the outline except a 1.2 mm connector lip, and placement_notes reports every part that could not be placed as asked. It still does not disclose job/async behavior or what a placement actually changes, so it stops short of rich behavioral context.

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 and engine, then a compact parenthetical constraint roll-up and the coarse-then-refine hand-off. Dense for 26 parameters but every clause is load-bearing; the nested edge/keepout parenthetical is slightly hard to scan.

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 26-parameter placer with no output schema, the description covers what the tool changes, what constraints bind it, and what it returns (placement_notes, the 1.2 mm lip exception). Gaps remain around placer vs refine selection and async job return behavior, which only the schema hints at.

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 81%, so the baseline is 3; the description earns above that by pinning semantics for the constraint families — fixed (exact origin and rotation, never moved), locked footprints, side, keepout rectangles, groups, near-with-maxMm, and edge syntax with optional '@mm' measured from the outline's top-left. It does not touch the refine-specific weights, which the schema covers anyway.

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 ('pack footprints inside the board outline') and names the engine ('Koppar's heuristic placer, ratsnest-driven, courtyard-legal'). It explicitly positions itself as the coarse pass whose output should be refined with place_footprints, which distinguishes it from place_footprints and anneal_place.

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?

Explains the default selection behavior (all unlocked move, locked stay) and when refs overrides it, plus the 'coarse by design: refine with place_footprints' routing. It never explicitly excludes anneal_place or place_footprints from the initial-placement role, so the sibling boundary is only half-drawn.

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