draw_rectangle

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

With no annotations, the description carries the full burden, and it does disclose real geometry behavior beyond the schema: centered placement, millimeter units, and that corner_radius uses real arcs rather than approximations. It says nothing about mutation side effects, undo/transaction semantics, permissions, or failure modes such as a missing sketch — significant gaps for a document-modifying call.

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

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

The one-line front-loaded purpose followed by an Args block is an efficient structure with no filler. Repetition of parameter names in the Args block is justified because the schema gives almost no descriptions to rival it.

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

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

With 7 parameters, no annotations, and an output schema the description need not explain, the geometry story is covered well. What is missing is the operational context — whether an active document/sketch is required, what instance selection implies, and what happens on failure — leaving an agent to infer preconditions.

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

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

Schema coverage is only 14%, so the description must compensate, and it largely does: it gives meaning to x/y as center coordinates, assigns mm units to width/height/corner_radius, and explains sketch_index (0 = latest) and corner_radius semantics including the slot case. The seventh parameter, instance, is left to the schema and defaults are not mentioned, but overall meaning is substantially enriched.

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

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

States a specific verb and resource — 'Draw a centered rectangle in a sketch' — with the centering convention and unit system (mm) made explicit. The rectangular shape plus the 'corner_radius ... = a slot' note separates it cleanly from draw_slot, draw_polygon, and draw_circle without needing to open their schemas.

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

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

Usage is only implied: 'in a sketch' and 'sketch_index: 0 = latest sketch' hint that a sketch must already exist, and the slot remark hints at when draw_slot is the better choice. There is no explicit when-to-use/when-not statement, no stated prerequisite like an active document, and no named alternative.

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