Editing & DRC

Beyond drawing from scratch, klayout-draw-mcp can open an existing layout, edit it, inspect it, and run simple design-rule checks. The typical loop is:

load_gds → inspect_gds → (edit) → drc_check → save_gds

These tools were added in 0.1.1.

Loading an existing layout

load_gds reads a GDS/OASIS file into the in-memory session, replacing any current layout. After loading you keep using the normal drawing tools (add_box, add_polygon, …) to modify it, then save_gds to write it back.

load_gds("chip.gds")                      # first top cell
load_gds("chip.gds", top_cell="PIXEL")    # a specific cell

Loaded chip.gds: top_cell='CIS_APS', dbu=0.001 um, 2 cells, 10 layers. Ready to edit.

Inspecting

inspect_gds reports, per layer, the shape count, merged area (so overlaps are not double-counted) and bounding box, plus the cell list. With a path it inspects a file without touching the session; without one it inspects the current session.

inspect_gds("chip.gds")

top_cell='CIS_APS', dbu=0.001 um, cells=2
bbox: (0,0;2,2) um
cells: ['APS_PIXEL', 'CIS_APS']

layer       shapes    area[um^2]   bbox[um]
2/0              4        4.0000   (0,0)-(2,2)
3/0             16        2.4192   (0.08,0.06)-(1.94,1.94)
4/0              8        1.0416   (0.57,0.05)-(1.95,1.95)
6/0             16        0.3936   (0.5,0.16)-(1.97,1.82)
9/0             12        0.3200   (0.62,0.06)-(1.95,1.94)
10/0             4        1.8000   (0.05,0.05)-(1.55,1.95)

Simple DRC

drc_check runs a list of rules against a file (path) or the current session and reports, per rule, PASS/FAIL with violation counts and locations. Distances are in micrometers; datatype defaults to 0.

Rule types

type	Parameters	Meaning
spacing	layer, min	Minimum space between shapes within one layer
width	layer, min	Minimum feature width on a layer
overlap	layer, layer2	Forbidden overlap — any intersection of two layers is a violation
separation	layer, layer2, min	Minimum space between two layers
enclosure	layer, layer2, min	layer2 must surround layer by at least min

Example

[
  {"type": "spacing",    "layer": 3, "datatype": 0, "min": 0.15},
  {"type": "width",      "layer": 6, "datatype": 0, "min": 0.08},
  {"type": "overlap",    "layer": 3, "layer2": 6},
  {"type": "separation", "layer": 3, "layer2": 10, "min": 0.05},
  {"type": "enclosure",  "layer": 3, "layer2": 10, "min": 0.02}
]

DRC: 5 rules, 3 failing
spacing 3/0 >= 0.15um: FAIL (8 violations)  at (0.550,0.692), (1.010,0.500), (1.820,1.000), (0.820,1.000)
width 6/0 >= 0.08um: PASS
forbidden overlap 3/0 & 6/0: FAIL (20 regions, 0.2784 um^2)  at (0.820,0.200), (1.820,0.200), (0.820,0.440), (1.820,0.440)
separation 3/0 <-> 10/0 >= 0.05um: FAIL (4 violations)  at (0.565,0.700), (1.565,0.700), (0.565,1.700), (1.565,1.700)
enclosure 10/0 of 3/0 >= 0.02um: PASS

max_report (default 10) caps the number of locations listed per rule.

Those locations can be drawn back as marker boxes to see exactly where the violations are. Here the OD spacing violations on the CIS pixel are highlighted on a marker layer:

Tip

The violation locations are centre points (in µm), so an assistant can read them back, decide what to move, edit with the drawing tools, and re-run drc_check — a closed correction loop.