Refill Zones

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

The description adds a crucial warning beyond the annotations: 'SWIG path has known segfault risk (see KNOWN_ISSUES.md).' This discloses a specific behavioral risk and directs to further documentation. It could go further by describing the operation's effects on existing fills, but the warning adds significant value.

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 two sentences: the first states the purpose, the second provides a warning and alternatives. Every sentence earns its place, and the information is front-loaded. No redundancy or fluff.

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 mutation tool with an output schema, the description covers the key aspects: what it does, the risk, and better alternatives. It might benefit from stating when to use it (e.g., after zone edits), but given the strong guidance, it is sufficiently complete.

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 no parameters, and the description correctly does not invent any. The phrase 'all copper zones' clarifies the scope of the operation, which is a helpful semantic addition. The baseline for zero params is 4, and this description meets it.

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 the action ('Refill all copper zones on the board') with a specific verb and resource, and it distinguishes itself from siblings like add_copper_pour or query_zones by focusing on refilling existing zones.

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 explicitly provides alternatives: 'Prefer using IPC backend (KiCAD open) or triggering zone fill via KiCAD UI instead.' This tells the agent when not to use this tool and which other methods to prefer, which is excellent guidance.

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