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

Annotations already declare readOnly/closed-world/non-destructive, and the description adds genuinely new context the agent could not infer: authentication is required, and no eligibility check or credit spend occurs. It does not cover caching or whether the guide content varies over time, but the safety and side-effect profile is fully clear.

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, zero filler. The return payload is front-loaded and the usage rule follows immediately, so an agent gets the gist in the first clause.

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?

An output schema exists, so return structure need not be re-explained; the description only summarizes it. Authentication and non-billing behavior are covered. The one remaining gap is how the returned guide connects back to the sibling execution tools, which the reader must infer.

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 description coverage is 0%, so the description must carry the load for the single `workflow` param. It says 'eight supported Magic Hour workflows', which matches the 8-value enum, but never explains what each choice selects or how to choose between, e.g., 'image-to-video' and 'video-generator' — the enum values themselves are the only guidance.

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?

Names a specific verb and resource (returns inputs/steps/examples/criteria for eight Magic Hour workflows) and states the scope explicitly as a planning artifact. The clause 'Use when planning a generation, not to run one' cleanly separates it from every create_*/generate_* sibling in the list.

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?

'Use when planning a generation, not to run one' gives an explicit when and when-not with the exclusion stated directly. It stops short of naming the concrete siblings to call afterwards (e.g. create_video_from_text), so the routing is implied rather than spelled out.

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