add_gp_stroke

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

With no annotations, the description carries the full burden and does so well: it discloses coordinate space, that a non-empty unknown layer name silently creates a layer, that empty material falls back to the object's first material, and that per-point radius tapers the stroke. It omits mode/context requirements (e.g., object mode) and any limits on how strokes interact with existing frame data, keeping it from a 5.

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 one-line purpose, then an Args block where each line carries distinct information. Slightly long, but no sentence is filler; the localized Args/Returns format is readable.

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?

An output schema exists and the description still summarizes the return (layer, frame, stroke count). Combined with thorough parameter semantics and disclosed fallback behaviors, an agent has everything needed to invoke correctly.

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 description coverage is 0%, and the description compensates fully: every one of the 7 parameters is explained semantically — point count bounds (2 to 10000), radius range (0.0001 to 10) and scalar-vs-array behavior, layer creation vs active-layer fallback, and frame meaning for animation. This is far beyond what the bare schema provides.

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+resource: 'Draw one stroke in a Grease Pencil object,' which is unambiguous. It does not, however, distinguish itself from sibling tools like add_annotation_stroke or create_grease_pencil, which an agent could plausibly confuse it with.

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?

Prerequisites are implied clearly through parameter notes ('from create_grease_pencil', 'create_gp_material'), routing the agent to the right setup tools first. There is no explicit when-not-to-use guidance or comparison to add_annotation_stroke, so it stops short of a 5.

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