canvas_guide

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

With no annotations, the description must carry the burden, and it does signal that this is instructional content to be consumed once before drawing, implying a static read with no side effects. It doesn't explicitly state read-only behavior or the nature of the returned text, but the framing as guidance-to-read is transparent enough for a zero-parameter tool.

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?

A single sentence delivers the topic list first and the usage condition second, with no filler. Every clause earns its place.

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 zero-parameter, no-output-schema documentation tool, the description covers what it contains, when to read it, and its one-time nature. There are no parameters or return values to explain further, so nothing an agent needs 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?

The tool takes no parameters, so the baseline of 4 applies. Nothing in the description conflicts with the empty schema and no input semantics are needed.

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?

The description names the resource (a canvas guide) and enumerates its content — layout, sizes, colours, and the live explain loop — which clearly separates it from the action-oriented siblings like canvas_draw or canvas_export. It lacks a crisp verb, but 'How to explain well on this canvas' leaves no ambiguity about what the tool provides.

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?

The clause 'Read once before your first drawing' gives an explicit trigger condition for when to invoke it, which is unusually actionable for a documentation tool. It doesn't name alternatives or say when not to call it, but the precedents it establishes are clear enough for an agent.

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