recommend-stackup

A printed-circuit-board layer review for KiCad, the software used to design electronic circuit boards. It recommends how copper and insulating layers should be arranged for signal quality and power connections.

In plain words
What is it for?
Use it to inspect a KiCad board's layers, check whether impedance targets can be manufactured, and provide routing settings for signal impedance and plane layers.
Why use it?
An untouched default layer arrangement can make signal-width and timing calculations differ from what a circuit-board factory will produce.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/drandyhaas/kicadroutingtools/recommend-stackup
Any agent
npx skills add drandyhaas/KiCadRoutingTools --skill recommend-stackup
Clone the repo
git clone --depth 1 https://github.com/drandyhaas/KiCadRoutingTools

Made for: Claude Code, Codex.

Per session 71 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 963 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00071 $0.00963
Opus 5 $0.00036 $0.00481
Sonnet 5 $0.00014 $0.00193
Haiku 4.5 $0.00007 $0.00096

Measured 3d ago against content hash e55ffbebfc32, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

recommend-stackup scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/recommend-stackup/SKILL.md · 58 lines

How it starts

The opening of the file, as written. The whole thing — 58 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Recommend Stackup

When this skill is invoked with a KiCad PCB file, review the stackup and recommend one suited to the board's impedance and plane requirements. The router's --impedance widths and --time-matching delays are computed from the stackup — a default stackup silently skews both.

Step 1: Read the Current Stackup

from kicad_parser import parse_kicad_pcb
pcb = parse_kicad_pcb('path/to/file.kicad_pcb')
for layer in pcb.board_info.stackup:  # List[StackupLayer], ordered top to bottom
    print(layer.name, layer.layer_type, layer.thickness, layer.epsilon_r)

Judge whether it looks deliberate or default:

  • No stackup section at all, or all dielectric layers with identical thickness and ε_r ≈ 4.5, suggests KiCad's untouched default.
  • Real fab stackups have distinct core/prepreg thicknesses (e.g. JLCPCB 4-layer: ~0.21mm prepreg, ~1.0mm core).

Report the verdict explicitly: "stackup appears to be KiCad's default — impedance calculations will not match your fab" vs. "stackup looks deliberate."

Step 2: Gather Requirements

  • Layer count and roles: copper layers from the board; which should be planes (GND/power) vs signal.
  • Impedance targets: from /identify-diff-pairs and /find-high-speed-nets results if available; otherwise infer from net names (USB 90Ω, LVDS/Ethernet/HDMI 100Ω, PCIe 85Ω, 50Ω single-ended for RF/clocks).
  • The fab: ask the user. If they name one (JLCPCB, PCBWay, OSH Park, Eurocircuits…), WebSearch its standard multilayer stackup and impedance-control offerings rather than inventing thicknesses.

Step 3: Recommend and Validate

Propose: layer assignment (e.g. 4-layer: F.Cu signal / In1.Cu GND plane / In2.Cu power-or-routable / B.Cu signal), dielectric thicknesses and ε_r per the fab's standard stackup, and copper weights. For impedance, what matters is the solid GND reference ADJACENT to each impedance-carrying layer — the other inner layer need not be a solid plane (on dense/BGA boards /recommend-plane-mappings will usually keep it split or routable; making BOTH inners solid planes is a minority human practice and starves dense boards of routing layers).

Read the full file on GitHub · 58 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 58 lines · 71 tokens per session scan A e55ffbebfc32

Subscribe to this mod's changes

recommend-stackup is a skill published in the GitHub repository drandyhaas/KiCadRoutingTools (372 stars, last pushed 3d ago), licensed MIT. It adds 71 tokens to every session and 963 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

zaptrace-design-validation

Validate a local ZapTrace design with requirements review, ERC/DRC evidence, and bounded engineering risk reports without claiming fabrication approval.

oaslananka/zaptrace · 31 tokens

bgp-registry-intel

BGP and registry intelligence — RPKI origin validation (is this announcement authorised?), RDAP registry ownership and abuse contacts, PeeringDB interconnection data, RIPEstat routing status and prefix visibility, RIPE Atlas anchors. Use when investigating an unfamiliar prefix or ASN, checking whether a BGP…

automateyournetwork/netclaw · 97 tokens

cad

Use when doing parametric 3D modeling, 2D drafting, geometric kernel development, BIM/IFC processing, PCB design, or AutoCAD .NET development. Index of 19 skills: FreeCAD, OpenSCAD, OCCT, CadQuery, KiCad, SolveSpace, QCAD, xBIM, Clipper2, TongWen and more.

znlgis/opengis-skills · 79 tokens

kicad

Use when designing electronic circuits and PCBs — schematic capture, PCB layout, 3D viewer, SPICE simulation, Gerber export. KiCad: the leading open-source EDA/PCB design suite.

znlgis/opengis-skills · 46 tokens

altium-library

Create and verify Altium schematic symbols (.SchLib) and PCB footprints (.PcbLib) from datasheets and 2D drawings, as code. Use whenever a part library must be made, fixed, measured from a drawing, or checked. Triggers: "make a footprint", "create a symbol", "add this part to the library", "SchLib", "PcbLib"…

ScottJeong/altium-claude-skills · 256 tokens

altium-pcb-placement

Altium PCB component placement — derive board size, decide rotation for main ICs and connectors, split zones, generate a 1:1 placement plan drawing, then inject real coordinates after approval, and check overlaps. Triggers: "PCB placement", "place the components", "how big should the board be", "board outline", "start…

ScottJeong/altium-claude-skills · 250 tokens