AutoCAD MCP Pro

Overview Schema Source Related Servers Discussions Admin

Understand: Describe Drawing

drawing_understand

Read-only

Analyze a DXF drawing or the current AutoCAD document without modifying it, returning a read-only report with evidence and confidence for units, extents, layers, rooms, blocks, and warnings.

Instructions

One report on a drawing somebody else made, every claim with its evidence and a confidence. Never modifies the drawing: a file is read as it is, and the current document through a snapshot (headless: the document in memory; live: a Document.Export DXF copy in a temporary folder, deleted after). An xref's own entities are not read - the host drawing is.

units: $INSUNITS as declared against the unit the geometry implies (text heights, wall thickness, door swings, labelled room areas, overall size - each item with its median and its value under every candidate unit). A disagreement is a warning with the numbers, never a silent correction.
extents: declared, computed and robust boxes and the outliers that stretch them, farthest first, by handle.
clusters: separate bodies of model-space content (plan copies, sheets, details), each with its box, entity count, commonest layers and tallest labels.
layers: entity count, drawn length (and metres in the inferred unit) and the discipline / service each most likely carries - the vocabulary's confidence (0.9) for a name keyword, 0.6 when most texts on the layer agree, 0.4 when fewer do.
equipment_tags (a tag found more than once is ambiguous), rooms (room labels in five languages, each with the wall-layer face it sits in and its measured area), languages (Latin / Turkish / Cyrillic character classes), blocks (named / anonymous, kinds by name), layouts, title_block and warnings.

Refused before anything is read: a path that does not exist, a DXF over MAX_DXF_BYTES (the refusal names the size and the variable), and a file the engine cannot parse (a DWG headlessly: ezdxf reads DXF only).

Input Schema

TableJSON Schema

Name	Required	Description	Default
`path`	No	DXF file to read (a DWG only on a live seat); omitted: the current document.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.6.0Sep 28, 2026

TDQS

A3.9/5.0

Behavior5/5

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

With only a readOnlyHint annotation, the description carries the burden and does so richly: it explains the snapshot mechanism (in-memory for headless, a temporary Document.Export DXF for live, deleted after), that an xref's own entities are not read, that the host drawing is, and preconditions for refusal (nonexistent path, MAX_DXF_BYTES with the variable named, DWG unparsable headlessly). This is behavior far beyond the annotation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The behavioral framing is correctly front-loaded, but the description then enumerates output fields (units, extents, clusters, layers, equipment_tags, rooms, languages, blocks, layouts, title_block, warnings) at length, which duplicates the output schema and bloats the definition. Only the confidence-scoring rules (0.9/0.6/0.4) and unit-disagreement behavior clearly earn their space.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only analysis tool with an output schema, the description supplies everything an agent needs beyond structured fields: mutation stance, snapshot semantics, xref handling, confidence conventions, and the exact refusal set. Nothing material to correct invocation is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and there is only one parameter, so the baseline is 3. The description reinforces path semantics (DXF read as-is; DWG only on a live seat; omitted means current document), but this largely restates what the schema field already documents, adding no new syntax or format detail.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The opening line states a specific verb and artifact: produce "one report on a drawing somebody else made, every claim with its evidence and a confidence." It clearly distinguishes itself from mutation siblings by declaring it never modifies the drawing. It does not, however, name or contrast itself against adjacent read/analysis siblings like drawing_info or analysis_layer_stats, so an agent must infer the split.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied rather than stated: the tool is for understanding an existing drawing read-only. There is no explicit when-to-use/when-not or named alternative among the many analysis siblings (validation_check, drawing_critique, drawing_info). The refusal conditions tell the agent what will fail, which is useful context but not selection guidance.

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

Deploy Server