fill_zones

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

The description goes far beyond the all-false annotations by disclosing a critical guarantee: 'the file that reaches the disk is the original with its zones' fills replaced and every other byte untouched,' explicitly listing what is preserved ('not its format version, not its layer names, not the constructs pcbnew does not model'). It also surfaces the pcbnew bindings dependency. No annotation contradiction exists.

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?

The description is model-like in structure: a crisp front-loaded subject-verb-object opening followed by a tight three-sentence behavioral paragraph, a one-line dependency note, and a labeled Args section. Every sentence earns its place.

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 single-optional-parameter tool with an output schema present, the description thoroughly covers what the tool does, how its side effects are bounded, what environment it requires, and how the parameter works. Nothing material is missing.

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?

Despite 0% schema description coverage, the description compensates by documenting pcb_path with its purpose ('Path to .kicad_pcb file'), optionality, and fallback semantics ('omit to use the configured default'). It adds meaning beyond the bare schema but does not go into extended detail beyond the single param.

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 opening line, "Fill all copper zones on the board using pcbnew's zone filler," uses a specific verb+resource+mechanism structure. It clearly differentiates this tool from sibling read-only/analysis tools and from zone creation tools like add_copper_zone.

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?

The description provides clear context about the operation and its non-destructive nature via the explanation that 'pcbnew computes the fill; this server writes it.' However, it never explicitly enumerates when-not-to-use scenarios or names alternatives, so it stops 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.