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AutoCAD MCP Pro
by U-C4N

Point: Intersection (deterministic)

point_intersection
Read-only

Computes the intersection of two AutoCAD LINE or CIRCLE entities, returning coordinates and flags for whether the point lies on each drawn segment; ref_x/ref_y picks between candidates.

Instructions

Compute the intersection of two geometry entities (LINE-LINE, LINE-CIRCLE, CIRCLE-CIRCLE). When two candidates exist, ref_x/ref_y selects the nearest.

Returns {x, y, on_first, on_second, on_both, candidates}. A LINE is intersected as the infinite line through it, so the point can lie beyond a drawn end: on_first / on_second say whether it lies on each drawn segment (a CIRCLE always holds its own intersection points) and on_both whether on both - check it before using the point as a corner. candidates is how many intersections existed. Refused, with the case named: parallel or coincident lines, a line that misses the circle, concentric circles, circles that do not meet, any other entity pair.

Input Schema

NameRequiredDescriptionDefault
ref_xNoReference X to pick nearest candidate when multiple exist
ref_yNoReference Y
handle1YesFirst entity handle (LINE or CIRCLE)
handle2YesSecond entity handle (LINE or CIRCLE)

Output Schema

NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.4.0

TDQS

A4.7/5.0
Behavior5/5

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

Goes well beyond the readOnlyHint annotation: discloses that a LINE is treated as infinite so the point may lie beyond a drawn end, explains the on_first/on_second/on_both flags and their reliability per entity type, and names every refusal case. This is exactly the non-obvious behaviour an agent cannot get from annotations or schema.

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

Conciseness5/5

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

Front-loaded with the verb and the supported pairings, then edge cases, then the return shape, then failures. Roughly 100 words for a tool with this many geometric caveats — no filler sentences.

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?

Even though an output schema exists, the description explains the semantic meaning of on_both and candidates (which a bare schema would not convey), covers the infinite-line trap, and closes with the full refusal surface. Nothing an agent needs to call this correctly is missing.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3, but the description adds meaning the schema lacks: it explains that ref_x/ref_y only matter when two candidates exist, and clarifies that handle1/handle2 accept any LINE or CIRCLE pairing while restricting which pairs are valid at all.

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

Purpose5/5

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

"Compute the intersection of two geometry entities" is a specific verb+resource, and the parenthetical enumerates the exact supported pairings (LINE-LINE, LINE-CIRCLE, CIRCLE-CIRCLE). That support matrix distinguishes it cleanly from near-neighbours like point_from_snap, point_tangent and construction_xline without the agent needing to open schemas.

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

Usage Guidelines4/5

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

Gives real operational guidance: ref_x/ref_y picks the nearest of two candidates, and "check it before using the point as a corner" tells the agent what to do with the result. The trailing refusal list effectively enumerates when-not cases (parallel, concentric, non-meeting circles). It stops short of naming an alternative sibling for those failed cases.

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

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