Paint: Pixel-art sprite from text rows

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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent mutation, so the safety profile is covered. The description adds a cross-cutting behavior note ('Layers, filters and undo work the same for every drawing tool') but says nothing about what a re-draw overwrites or the preview/opacity effects.

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?

Front-loaded with the core mechanism in the first sentence, then a short second paragraph on targeting and shared behavior. Tight and purposeful, with only the 'Perfect for...' clause bordering on filler.

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?

For a 10-param tool with nested palette objects and no output schema, the description explains the drawing model and cross-cutting layer/filter/undo behavior well. Minor gaps remain around preview/opacity/blend, though those are largely documented in the schema.

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 70% and the description meaningfully extends it: the character→colour lookup rule, the skip set ('space and `.`'), the cell block sizing, and the origin start point, which frames how rows/palette/cell/origin interact. It adds real semantics beyond the schema for the core params.

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?

State a specific verb and resource ('Draws a sprite') and explains the exact mechanism: each character of `rows` maps through `palette`, skipped chars, and a `cell`x`cell` block at `origin`. This is specific enough to distinguish it from siblings like paint_pixels, paint_stamp, and paint_rect without opening any schema.

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?

Gives clear context — 'Perfect for sprites, tiles, icons and logos' — and states the canvas prerequisite ('created with paint_canvas') plus the optional layer index. It stops short of naming when to prefer this over the close sibling paint_pixels or when not to use it.

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