calculate_pcb_stackup_impedance

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 needs no coverage here. The description usefully adds that the underlying model is IPC-2141A and enumerates the supported target impedances, but says nothing about accuracy limits, frequency dependence, or what a solved width looks like.

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?

A single front-loaded sentence that leads with the lookup action before the solve action. It is dense with parenthetical model numbers and per-interface values, but every element is substantive and nothing is redundant.

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 is the only place the return payload could be characterized, yet it never says whether the result is a stackup matrix, a computed trace width, or both. For a two-mode tool (preset lookup plus custom solve) that ambiguity leaves an agent guessing at the response shape.

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% and the enum for stackup_id is fully documented in the schema, so the baseline is 3. The description contributes only marginal extra meaning by tying the impedance targets (50/90/100/120Ω) to the custom-solve parameter, without explaining units, ranges, or whether the custom value overrides the preset list.

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?

States a specific verb (lookup/solve) and resources (4-layer and 6-layer stackup matrices, controlled-impedance trace widths), and names the concrete stackup models JLC04161H/JLC06161H. It does not explicitly distinguish itself from the closely-related siblings calculate_trace_impedance and analyze_impedance_tolerance, so an agent still has to infer which one applies.

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 implies when it applies (standard industrial stackups, common interface impedances such as USB/Ethernet/CAN), but gives no explicit when-to-use or when-not-to-use guidance and never names the alternative tools for impedance work. Usage is inferable from the impedance targets listed rather than stated as a routing rule.

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