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

With annotations present, the description still adds real behavioral context beyond them: nothing is generated, no credits are spent, and no sign-in is required to prepare. The annotation set (readOnlyHint=false, idempotentHint=false) does not convey the cost/auth profile, so this text is load-bearing. It stops short of describing what the returned 'settings and credits required' actually contain or what the agent should do next.

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 purpose, then cost/auth behavior, then the exclusion and routing rule — a sensible order with no filler sentences. The final exclusion sentence is long and packs several modalities, but every clause carries distinct routing information.

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?

Coverage of auth, cost, non-generation and exclusions is strong, and an output schema exists so return values need not be spelled out. The gap is workflow: the description never says the preparation is a precursor to an actual render or which sibling to call next, which matters given siblings like generate_media.

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 100%, so a baseline of 3 applies, but the description adds meaning by framing headline and details as text 'printed on the design' (with examples like date, place, offer) and by tying theme/format to the visual output. The text-only restriction also implicitly constrains how these parameters may be used, which the schema alone does not say.

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 states a specific verb and resource ('Prepare a poster or flyer design with Abracadabrax') and enumerates the concrete inputs that define the output (headline, details, theme, format). It also explicitly carves out what the tool is not for, so an agent can separate it from image-generation siblings without opening the schema.

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 gives explicit when-to-use (text-only poster/flyer with headline plus details) and when-not-to-use (uploaded, attached or reference images/videos: editing, background removal, upscaling, image-to-video), and names the correct destination for those cases ('point the user to the Abracadabrax workspace'). This is exactly the routing guidance an agent needs.

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