list_diff_pairs

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds real value by disclosing that the skew limit defaults to the design's dpMaxLengthDifference rule, but it offers no other behavioral context (e.g., scope of the design it reads).

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 tight sentences with no filler, and the returned-field list is front-loaded before the parameter default note. Slightly telegraphic but every phrase carries information.

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?

An output schema exists, so return values need not be spelled out, and the description covers the resource and the one parameter's default behavior. A note about which design context it operates on would make it fully self-contained.

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% for the single max_skew_mm parameter, so the description must compensate, and it does: it explains that the skew limit defaults to the design's dpMaxLengthDifference rule, giving the parameter meaning the bare schema lacks.

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 identifies the resource (differential pairs identified by _P/_N naming) and enumerates the per-side attributes returned (length, skew, width, gap, vias). The verb is implied by the name rather than stated, but the scope is specific enough to distinguish it from list_nets/get_net.

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?

There is no guidance on when to use this versus siblings such as check_length_match, route_pair, or list_nets, nor any stated prerequisites (e.g., an open design). The agent must infer usage from the name alone.

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