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

Goes well beyond the annotations (which only say non-read-only, non-idempotent, non-destructive) by disclosing the async lifecycle ('Returns generating, never finished'), the all-or-nothing success condition, the billing/accounting effect ('Counts as one post'), and the safety guarantee ('Never publish automatically'). These are exactly the behavioral traits an agent needs before invoking a generation 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?

Front-loaded with the core action and cardinality, and each subsequent sentence carries distinct information (routing, brief requirements, alternative tool, lifecycle, publish behavior) with no filler. It is dense and slightly list-like, but nothing is redundant.

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?

With no output schema and thin annotations, the description supplies the return semantics, the draft-promotion condition, and the no-auto-publish guarantee. Remaining gaps are minor parameter explanations (topic, characters) rather than anything that would cause a misinvocation.

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 has to carry the load and it does for the key nested fields: it explains that each slide needs a distinct complete brief preserving subjects and shared constraints, and instructs on productId and referenceImageIndex usage. It leaves 'topic' and the 'characters' array undocumented, so it does not fully close the coverage gap.

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 ('Create ONE carousel post containing 2-10 separately generated photos, in the requested order'), including scope and ordering. It explicitly distinguishes itself from the closest sibling by naming create_carousel_from_images, so an agent can route correctly without opening either 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?

Gives explicit when-to-use ('when the user asks for an image/product/photo carousel') and when-not ('not separate posts or a text slide deck'), plus the alternative for the adjacent case ('Original photos without AI changes use create_carousel_from_images instead'). Nothing is left to inference.

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