Not a mockup. Every line on this sheet was drawn by the tools this server exposes — ISO layers, involute gear geometry, DIN 6885 keyway, section A-A, ISO 129 dimensions, an ISO 286 H7 bore fit, ISO 7200 title block — then rendered headlessly by view_screenshot. drawing_critique returns 0 issues on it. Rebuild it with python scripts/render_readme_showcase.py.
A mechanical sheet, gated. The mech_assembly benchmark sheet: a hub drawn from its part model with a full section and chain dimensions, a flange with its bolt-circle end view, two ISO 4014 M12×60 bolts and ISO 4032 nuts inserted as blocks, the ISO 7573 parts list read off the drawing, balloons linked to its rows, an ISO 5457 frame and an ISO 7200 title block. drawing_critique(focus=None) returns 0 issues and the finalize score is 100. Rebuild it with python scripts/render_readme_mech.py.
A floor plan whose areas nobody typed. arch_plan_from_spec's example, drawn in one transaction: a 250 mm brick ring split by a 100 mm AAC wall, two doors, two windows, a straight stair and exterior dimension chains at 1:50. The rooms measure 27.74 and 21.99 m², read from the faces the walls enclose, and the door, window and room schedules are read off the drawing. drawing_critique(focus=None) returns 0 issues. Rebuild it with python scripts/render_readme_arch.py.
The same server as a P&ID drafter. pid_from_spec placed five catalogue symbols as real blocks with TAG attributes and named ports and routed four port-to-port lines with ISA-5.1 classes and line numbers, all in one transaction. Then pid_graph read the sheet back: 5 nodes, 4 edges, 0 dangling ends, confidence_min 1.0. Rebuild it with python scripts/render_readme_pid.py.
The catalogue, authored in code. 43 ISO 10628-2 / ISA-5.1 symbols: 11 valve bodies × 6 actuators, 6 rotating machines, 4 heat exchangers, 6 parametric vessels, 7 inline items, the instrument bubble in 4 types × 5 locations, 5 line markers and 3 connectors. Every one was placed through pid_symbol_insert's own path. Rebuild it with python scripts/render_pid_catalog.py.
TOOL_PACKS=core hides these from a client that needs none of them: the nine pid_* tools, the 22 environment tools, the 14 mechanical tools, the 12 architectural tools and the two plant takeoffs. TOOL_PACKS=core,mech keeps the mechanical ones, TOOL_PACKS=core,arch the architectural ones, and TOOL_PACKS=core,plant the takeoffs. There are also 8 resources that cost nothing in the tool budget (autocad://drawing/info, layers, blocks, entities/stats, entities/{layer_name}, system/status, pid/symbols, standards/isa51) and 5 prompt templates.
**Two rules worth knowing.**
- Every coordinate in and out of a tool is WCS on both engines. The one exception is TEXT `rotation`, which stays in the entity frame: a mirrored TEXT is mirror-imaged, and no scalar angle expresses that.
- Never read vertices back and shoelace them. That silently loses **28.2%** of the area on a semicircular edge. `analysis_measure_entity(handle)` reads the real geometry and states its own accuracy.
## The two engines
One contract across 23 modules in `backends/contracts/`. `@capability(key, reason=…)` supplies a default that *refuses*, and a test holds both backends' capability key sets equal. There are **41 capability keys**. Read `system_capabilities` at runtime rather than trusting the table: several depend on what the machine has installed (matplotlib, openpyxl, the ODA File Converter).
| Capability | COM (live AutoCAD) | ezdxf (headless) |
|---|:---:|:---:|
| Live document control | ✅ | — |
| Cross-platform, no AutoCAD | — | ✅ |
| Transactions and rollback | ✅ | ✅ |
| Paper-space layouts + viewports | ✅ | ✅ |
| Viewport model-content rendering | ✅ | ✅ ᵐ *(no borders)* |
| Selection window / crossing / polygon | ✅ | ✅ |
| Entity area by handle | ActiveX `.Area` | Analytic, bulges included |
| HATCH filled area (islands subtracted) | AutoCAD's own number | Loops walked, `hatch_style` reported |
| REGION / 3DSOLID area | ✅ | — *ACIS is opaque to ezdxf* |
| 3D solids | ✅ *with `ENABLE_3D=true`* | — |
| DWG write | ✅ `SaveAs` | via the ODA File Converter, if installed |
| `.dwt` templates | ✅ | DXF only — `dwt_write` refuses |
| Reading a foreign drawing (`drawing_understand`, takeoffs) | ✅ one `Document.Export` snapshot; the document is never renamed | ✅ |
| XLSX workbooks | ✅ ᵒ | ✅ ᵒ |
| Preferences · launch · operator prompts | ✅ | — *refused by name* |
| WIPEOUT · MTEXT background colour | — *verified absent, AutoCAD 2026* | ✅ |
| REVCLOUD · BPOLY · typed hatch edges | — *no ActiveX member* | ✅ |
| CHSPACE | — *unverified on a live seat* | ✅ ᶜ |
| Undo history | ✅ | opt-in — `EZDXF_UNDO_DEPTH` |
| TABLE and MLEADER | Native | Portable composite |
| Screenshots and PDF | Window capture | Matplotlib ᵐ |
ᵐ Needs matplotlib ([pdf]/[full]). Without it, png, pdf, viewport_render and handle_overlay report unsupported headlessly.[office]/[full]). Without it, XLSX is refused with xlsx_write and CSV is still written.
A fixed 100-point rubric applied to nine public AutoCAD MCP servers ([`source_review.json`](https://github.com/U-C4N/Autocad-MCP/blob/main/benchmarks/source_review.json)). Stars and raw tool counts score nothing. 1.6.0 is scored **per category, with the evidence for every point withheld**:
| Category | Weight | 1.6.0 | Points withheld for |
|---|---:|---:|---|
| Functional CAD coverage | 25 | 24 | no electrical schematics, image-to-CAD tracing, Plant 3D, obstacle-avoiding routing or headless REGION / 3DSOLID |
| Correctness and delivery | 20 | 19 | a headless DIMENSION does not re-render; a takeoff on a real P&ID still needs the engineer's scope decisions |
| Backends and platforms | 15 | 14 | BricsCAD, ZWCAD and GstarCAD unverified |
| Engineering production | 15 | 14 | four DIN / ISO feature tables ship empty |
| Tests and maintenance | 15 | 14 | headless entity creation slower than v1.4.0 |
| Security and operations | 10 | 8 | `ALLOWED_PATHS` unscoped by default; command filtering is a denylist |
| **Total** | **100** | **93** | |
> [!NOTE]
> Read this as a documented self-assessment, not an independent review: this repository applies the rubric to itself and to the others. The competitor rows are their July 2026 snapshots and were not re-reviewed for this release, and the best of them, varavista/autocad-mcp, scored 84. 1.4.0 was given one overall 95. This review is stricter and scores each category apart.
A second lane runs tasks instead of reading source. Every task in the fixed-task matrix can fail, and its artifacts are verified by re-opening the DXF, never by trusting a response. The reference adapter passes **21 / 21** of matrix v7. The two competitors with adapters, pinned at their July 2026 commits, passed 5 / 10 and 4 / 10 of the ten v2 tasks they were run on. The eleven tasks added since then were never put to them, so they show as *not run*, not as zero:
### Correctness — every release re-proves itself
48 deterministic headless checks against the previous tag and the current tree. Each runs in its own subprocess, so a hard crash counts as a miss rather than killing the run.
| Version | Checks passing | Pass rate | Fixed | Regressed |
|---|---:|---:|---:|---:|
| v1.5.1 *(baseline)* | 26 / 48 | 54.2 % | — | — |
| **v1.6.0** *(this release)* | **48 / 48** | **100 %** | 22 | **0** |
The 26 checks v1.5.1 was released on all still pass. The twenty-two fixed rows are new capability (`miss → pass`), and each one pins a number computed by hand, not read back from the code that drew it:
The workloads call the same backend methods the MCP tools call, so server-side overhead is included. Numbers move with hardware; the report records the machine fingerprint. **Read the next section before quoting them.** This release is slower than v1.4.0 at creating entities.
## What this release is bad at
A page that only lists strengths is a page that has not been measured.
**Headless entity creation is slower than v1.4.0, and 1.6 did not win it back.** These are medians of five alternating runs on one machine, with one interpreter (CPython 3.11.15) and one ezdxf, v1.4.0's code against 1.6.0's ([`perf-v1.4.0-vs-v1.6.0.json`](https://github.com/U-C4N/Autocad-MCP/blob/main/benchmarks/results/published/perf-v1.4.0-vs-v1.6.0.json)):
| Workload | v1.4.0 | v1.6.0 | v1.6.0, `EZDXF_CALL_TIMEOUT=0` |
|---|---:|---:|---:|
| 2,000 lines, one call each | 244.5 ms | 306.1 ms (1.25×) | 284.9 ms (1.17×) |
| 10,000 lines: build, DXF export, reopen | 1,847.9 ms | 2,553.5 ms (1.38×) | 2,216.4 ms (1.20×) |
| Region query over 10,000 entities | 665.2 ms | 712.2 ms (1.07×) | 783.9 ms (1.18×) |
| Premium quality pass | 150.6 ms | 65.3 ms (**2.3× faster**) | 69.9 ms |
The per-call timeout stops one hung call from wedging a server whose document lock is a single `asyncio.Lock`. It explains only part of the slowdown: switched off, creation is still 1.17× and 1.20× slower. The rest is extra work per call that 1.6 has not removed. A cProfile of the event-loop thread counts 491,071 function calls for the 2,000 creates, against v1.4.0's 319,038. Earlier READMEs said that switching the timeout off returned creation to v1.4.0's numbers. Measured this way, it does not. The region-query row, which moves the wrong way, shows this machine's noise floor (about ±10 %). Roadmap criterion 7 is not met and moves to 1.7.
**Four mechanical feature tables ship empty.** DIN 471/472 retaining-ring grooves, DIN 509 undercuts, DIN 332 centre holes and ISO 3601-2 O-ring grooves have their drawing code and their provenance tests, but no rows. A groove diameter written from memory is a wrong workshop drawing, while a narrow table is merely narrow. So every size is refused by name until rows verified against the standard's own table are transcribed. That is a data edit; each module's docstring says how.
**Takeoffs are estimates, and they say so.**
- A layout length is the rectilinear minimum spanning tree of the tags a run connects, plus a stated vertical allowance, and it is labelled an estimate.
- A P&ID length is used only when `drawing_scale_check` calls the P&ID to scale.
- A power the P&ID does not state stays empty and becomes an open item, and no cable-section table is authored: a section comes only from your `section_rules`.
- Where no callout names a panel, the nearest panel is inferred and flagged.
- Detail copies of equipment are flagged, and excluded only when you ask.
The readers were tuned on the synthetic plant pair and on one real P&ID / layout pair that is not in this repository. Another drafting office's layer and text conventions may need vocabulary.
**No Plant 3D.** The roadmap's track D (read-only queries of a Plant 3D project) was dropped: the maintainer does not use Plant 3D, and a reader tested against nobody's real projects would be a guess. Roadmap criterion 5 is withdrawn, not met.
**No REGION or 2D booleans headlessly.** `add_region()` produces a REGION with **zero ACIS bytes**, and the `greiner_hormann` substitute loses **28.2%** of the area on a square with one semicircular edge.
**`system_run_command` / `system_run_lisp` are a guardrail, not a security boundary.** The rejection message says so in those words. A 36-verb denylist refuses the obvious cases, but AutoCAD accepts hundreds of commands, and `DANGEROUS_COMMANDS_ENABLED=true` switches the list off entirely.
**Path validation is per-tool, and unscoped until you scope it.** With `ALLOWED_PATHS` empty (the default), the only positive bound is a ten-entry system-directory denylist that does not include `C:/Users`, `/home`, `/root` or `/var`. **Set `ALLOWED_PATHS`.**
**Non-AutoCAD ProgIDs are unverified.** `CAD_PROGID` changes which COM application the backend attaches to; nothing beyond the connection has been tested against BricsCAD, ZWCAD or GstarCAD.
### Known limitations of the P&ID track
**The router is orthogonal and blind.** `pid_line_draw` picks `auto` from seven orthogonal candidates, by fewest bends then length:
- straight;
- one bend;
- two bends through the midline;
- a stub out of each port joined by three bends.
You can also take `direct`, or pass waypoints. It *counts* the lines it crosses (`crossings` comes back in every result, and `pid_from_spec` sums it), but it does not route around them. Obstacle-avoiding routing is not in 1.6; move the symbol or pass waypoints.
**A foreign drawing is read at the confidence it earns, and no higher.** A block this server did not place classifies at 0.6, with inferred ports, by its `TAG`-style attribute or a keyword in its name. It classifies at 0.3 when a line merely touches it, and a 0.3 guess can neither raise nor suppress a critique finding.
On the live engine, an INSERT turned off a right angle has members ActiveX cannot measure, so it reports an *approximate* box. `pid_graph` takes the tighter wall of that box and the attribute-inclusive box on every side. Even so, a line ending on such a body's true edge can still be reported `dangling`, with the nearest port as the hint. Read `stats.confidence_min` first.
**Same-file only, DXF headlessly.** Off-page connectors link within one drawing; links across files are not resolved. The headless engine reads DXF; a DWG P&ID is read through the live backend. There is no DEXPI/Proteus export and there are no ISA-5.2 binary-logic symbols in this release. Both cuts are recorded in the spec so nobody re-derives them.
### Known limitations of the settings track
**Layer states are ours.** `layer_state_save` writes a portable snapshot into an `ACADMCP_LAYERSTATES` XRECORD. It survives save/reopen on both engines and travels with the DWG/DXF. It is **not** an AutoCAD `LAYERSTATE` and does not appear in the Layer States Manager, which is why `system_capabilities` reports `layer_states` as `mode: "xrecord"`.
**Six of the 22 environment tools need a live seat.** Preferences, launching, the operator prompts and the five summary fields of document properties are refused headlessly with `preferences` / `dwgprops` / `live_application` / `interactive_prompt`. Each is a refusal, not a stub.
A `.dwt` template is the same case (`dwt_write`): a `.dwt` is a DWG container, so headlessly the template is saved as DXF. `mleaderstyle_create` is *not* such a case. ActiveX has no MLeaderStyle collection, but the `ACAD_MLEADERSTYLE` dictionary holds full `IAcadMLeaderStyle` objects, so both engines create leader styles.
**A headless dimension does not re-render.** On the ezdxf engine, `dimstyle_modify` reports `dimensions_using_style` and `rerender_required: true`, and the DIMENSION keeps its rendered block until it is redrawn. AutoCAD regenerates on the next regen.
### Known limitations of the architecture track
**Nominal, not standard.** The furniture and sanitary blocks carry nominal catalogue sizes and say so. The stair tool reports the Blondel relation (2R + G within 600–650 mm) as a design rule, never as a building code. The `arch` layer colours are a repository convention: ISO 13567 fixes the names, not the colours. Labels speak English or Turkish; any other `lang` is refused with the list.
## Configuration
Nothing loads a `.env` file — export these, or set them in your MCP client's `env` block.