set_canvas_font

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

With no annotations provided, the description carries the burden of disclosing behavioral traits. It explicitly says the font updates every existing element immediately and persists as the default for new elements. It also provides semantic meaning for font choices (hand-drawn, clean standard, classic sketch). While it doesn't discuss undo or reversibility, the core side effects are well covered.

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 description is two sentences long, front-loads the main action, and every sentence earns its place. The first sentence states the action and its immediate effect, the second clarifies persistence and provides helpful font semantics. No wasted words.

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 single-parameter tool with no output schema, the description is fully complete. It covers the tool's purpose, scope, immediate effect, persistence, and offers user-friendly font hints. There is no ambiguity about what happens when this tool is invoked.

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 schema provides 100% coverage with descriptions for each numeric font value, but the description adds qualitative meaning (e.g., Excalifont = hand-drawn, Helvetica = clean standard, Virgil = classic sketch) that helps the agent understand which font to choose. This goes beyond the schema's literal mapping.

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 uses a specific verb 'Set' with a clear resource 'global font' and scope 'ALL elements on the canvas'. It immediately distinguishes this from per-element editing tools like update_element, making the tool's purpose unambiguous.

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 description clearly states the global scope and that it updates all elements, which implies when to use it—when you want a canvas-wide font change. However, it does not explicitly mention alternatives or when not to use it, only that the effect is global and persistent.

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