pcb_place_region

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

With no annotations, the description carries the burden and does disclose a non-obvious behavioral trait: regions do not participate in the connectivity engine unless a net is assigned. It does not state what happens on overlap with existing copper, whether placement is additive or overwriting, or whether it can be undone, which matters for a mutation tool.

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 purpose, then a short rationale, then args. Mostly tight, but the "Returns: Dictionary confirming the region placement" line is redundant since an output schema exists, and the prose wraps more than needed.

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?

Return values are covered by the output schema and need not be described, and all six parameters are explained. What's missing for a board-mutating placement tool is any statement of preconditions (active document/board required) or failure modes.

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 0%, so the description must compensate, and it does: it documents units (mils), that corners may be given in any order, the layer default and accepted layer kinds, and that net is optional. It stops short of enumerating valid layer names or explaining what an empty net string means.

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 ("Place a solid copper region on a rectangular area") and immediately differentiates the primitive type from polygons. An agent can distinguish this from pcb_place_polygon_rect or pcb_place_fill without opening any 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 explicit positive use cases (mechanical copper zones, thermal pads, solder-mask openings) and an explicit negative/alternative routing rule: use pcb_place_polygon_rect for a true ground plane with ratsnest tracking. This is a full when/when-not/alternative statement.

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