fill_zones

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

Annotations (readOnlyHint=false, destructiveHint=false) indicate a non-read-only, non-destructive modification. The description adds the requirement for pcbnew Python bindings, which is useful. However, it does not specify that the tool modifies the .kicad_pcb file in place, nor mention idempotency or side effects (idempotentHint=false). Given annotation coverage, a 3 is appropriate.

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?

Two sentences plus an Args list. The first sentence states purpose, the second adds a key requirement. No wasted words, front-loaded, and easy 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?

The tool has an output schema (not shown), so return values are not needed. However, with only one parameter (pcb_path) that has a default empty string and is not required, the description does not clarify whether an empty path is valid or if the tool requires a path. It also lacks workflow context (e.g., should be called after adding zones). Given low schema coverage and no behavioral details beyond a requirement, completeness is insufficient.

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. It lists 'Args: pcb_path: Path to .kicad_pcb file', which adds basic meaning beyond the schema type. However, it does not specify constraints (e.g., file must exist, default behavior if empty). The parameter name is self-explanatory, so this minimal addition merits a 3.

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?

The description clearly states 'Fill all copper zones on the board using pcbnew's zone filler.' This provides a specific verb and resource, distinguishing it from sibling tools like add_copper_zone (adds zones) and list_pcb_zones (lists zones). No ambiguity.

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?

No guidance on when to use this tool versus alternatives. While it mentions a requirement (pcbnew bindings), it does not specify prerequisites (e.g., zones must exist) or when not to use it. Sibling tools like add_copper_zone exist but no comparison is given.

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