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

Annotations cover the safety profile (destructiveHint false, openWorldHint false), and the description adds genuine behavioral detail beyond them: the exact metrics reported (narrowest track, length below class width, coupled share at diff_pair_gap, skew), the pair patterns recognized, and that routing applies the same rules. It is consistent with the annotations, though it never explains the non-read-only stance or the async job behavior.

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 purpose is correctly front-loaded and no sentence is wasted, but the core sentence is a dense colon-list run-on packed with parenthetical patterns and metrics that is hard to parse in one pass. It earns its length through real technical content but could be structured more readably.

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?

With no output schema, the description usefully enumerates what the check reports (narrowest track, below-width length, coupled share, skew), which is the key missing piece. Remaining gaps, the async job lifecycle and result shape, are partly covered by the wait_s schema text pointing to get_board_job.

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 100%, so both parameters (design_id, wait_s) are already fully documented in the schema. The description adds no parameter-level detail such as accepted id origins or wait semantics, so the baseline 3 applies.

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 states a specific verb and resource ('Check the copper against the project's net classes and differential pairs') and explicitly carves out the niche it fills versus a named sibling concept ('which KiCad's DRC does not'). An agent can distinguish it from run_drc, check_physics, or diagnose_open_nets 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?

It gives clear context for when this tool is the right one (net-class and diff-pair checks that DRC omits), which implies its place among the check_* siblings. It stops short of naming an alternative tool or stating when NOT to use it, so it is a strong 4 rather than a 5.

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