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

With no annotations, the description carries the full burden; it does usefully disclose the return artifacts ('Returns SVG + PNG'), which is the main behavioral fact an agent needs. But it says nothing about whether the mascot referenced by id must already exist, whether generation is synchronous or a job requiring wait_for_job (a sibling that hints at async flows), or what happens on failure.

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?

Two sentences, action and output, with the artifact returned front-loaded second where an agent will read it. There is no filler, hedging, or repetition of the title.

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 4-parameter generation tool with no annotations and no output schema, the definition covers the essentials of what it makes and what it returns. It still leaves material gaps: the meaning of the required id, whether the mascot must exist first, and whether output arrives directly or via a job are all unaddressed.

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 50%: prompt and animation are documented in the schema, while id is entirely undocumented and size only carries an enum plus default. The description adds no parameter-level meaning at all—it never explains what id refers to, how animation interacts with the scene prompt, or what the size options produce—so it does not compensate for the coverage gap, but the enum and default keep it at the minimum-viable baseline.

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 and resource ('Place the mascot in an illustrated, fully vector scene') and names concrete deliverables (hero banner, empty state, social card), which tells an agent this produces composed scene layouts rather than a bare mascot. It does not explicitly distinguish itself from siblings like create_canvas or create_clip, so it stops short of a 5.

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 parenthetical examples (hero banner, empty state, social card) imply the situations the tool is for, which is more than nothing. However, there is no explicit when-to-use versus when-not, and no mention of the alternatives (create_canvas, animate_mascot, add_prop) that an agent must choose between in this crowded sibling set.

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