set_background

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

With no annotations, the description carries the full burden and does it well: the colour is shown exactly as given and never inverted, the default pen follows it so the next stroke is visible, existing elements are unaffected, and new scenes default to #121212. It stops short of stating permissions, return value, or reversibility (though snapshot/history siblings exist).

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?

Four tight sentences, front-loaded with the core action and followed by consequences; each sentence carries a distinct warning (inversion, pen default, element persistence, default colour). Slight redundancy in 'the scene's real background colour, shown exactly as given (never inverted)'.

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 3-required-parameter mutation tool with no annotations and no output schema, the description covers the important side effects and defaults. It omits reversibility/undo behaviour and any note on failure modes, but nothing critical for correct invocation is missing.

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?

Two of three parameters are documented in the schema (scene, label) for 67% coverage; color has no schema description, and the description adds only indirect meaning about colour behaviour rather than format or accepted values. Baseline 3 is appropriate given the schema already handles most parameter documentation.

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: setting the scene's background colour, with 'paper' clearly defined as the real background colour. It is readily distinguishable from siblings like update_elements or replace_scene. Scope is unambiguous at first sentence.

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?

It implies the use case (flipping a scene from light to dark or back) and warns that existing elements keep their colours so you must recolour ink yourself, but it never names the sibling tool to use for that (e.g. update_elements) nor states when-not to use this tool. Guidance is implied rather than explicit.

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