list_zones

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

Annotations already indicate readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: it explains that unfilled zones do not electrically connect until a refill is run, which goes beyond the raw annotation fields. This enriches the agent's understanding of the domain.

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 four sentences long, front-loaded with the core listing purpose, and every subsequent sentence earns its place by explaining zone terminology and fill behavior. There is no redundancy or padding.

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 zero-parameter listing tool with an output schema and strong annotations, the description fully covers the domain concepts needed to interpret the results. It explains what zones are, what the fill status means, and the operational implication of unfilled zones. No significant gaps remain.

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?

There are zero parameters, so the schema provides no burden. The baseline for 0 parameters is 4, and the description adds semantic detail about the returned data (net, layer, bbox, fill status), making the tool's output expectations clear.

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 uses the specific verb 'Lists' and identifies the exact resource ('all copper zones on the PCB board'), then enumerates the key attributes returned (net, layer, bounding box, fill status). This clearly distinguishes it from sibling tools like list_footprints, list_nets, and list_tracks.

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 when zones are relevant (ground planes, power distribution) and explains the semantic difference between filled and unfilled zones, implying when this tool is useful. However, it does not explicitly name alternative tools (e.g., manage_zone for modifications) or state when not to use it, stopping 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.