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

Annotations only supply the generic hint set (readOnlyHint=false, destructiveHint=false, idempotentHint=false, openWorldHint=false). The description adds non-obvious behavior the annotations cannot convey: images are cropped to portrait format, the operation yields a draft (not a published post) plus ownerLink and reviewLink, and the images must be publicly reachable URLs. The ownerLink warning about this chat's inability to render images is exactly the kind of context an agent needs.

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?

Purpose is front-loaded, constraints follow, then return values, then the critical ownerLink instruction last for emphasis. Four sentences, all information-bearing, no filler.

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, the description carries the burden of explaining returns and does so concretely (draft post, ownerLink, reviewLink) while also explaining the required user hand-off. Combined with a fully documented input schema, nothing an agent needs to invoke and correctly relay results is missing.

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 100%, so imageUrls, caption and context are already documented, including the 2-10 bound and slide ordering. The description largely restates this (image count, public URLs, caption-or-context choice) rather than adding syntax or format detail beyond the schema; baseline 3 applies.

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 a carousel post from 2-10 images (public URLs)') and adds scope constraints that make the tool's input contract immediately clear. However, it never distinguishes itself from the several other carousel-creating siblings (create_carousel, create_photo_carousel, create_facebook_product_carousel), so the agent must infer the routing from the input requirements alone.

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 clear operational guidance: supply either a ready caption or a context for AI generation, and the emphatic 'ALWAYS give the user the ownerLink' instruction with its rationale (chat cannot display images). It stops short of explicit when-to-use/when-not-to-use guidance relative to the carousel siblings.

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