Publish a carousel

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

Annotations already declare readOnlyHint=false, idempotentHint=false and openWorldHint=true, and the description adds genuinely non-derivable facts: the daily-limit accounting, the env-var write gate, and the pending-container_id return that requires a follow-up call. It doesn't discuss idempotency directly (whether re-calling with the same container_ids republishes or completes the original), which is the main remaining unknown for a non-idempotent mutation.

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?

Three dense sentences, front-loaded with what the tool does, then the limit accounting, then the failure/retry behavior. No filler and no 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 3-parameter write tool with no output schema, it covers the write gate, the limit cost, and the non-happy-path return shape. It doesn't say what a successful publish returns (media id), which would be the last piece an agent needs to chain a follow-up call, but nothing required to invoke it correctly 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 67%, and the description compensates for the hardest part: it explains that items accepts image and/or video entries and that a returned child container_id can be fed back in as an item, which the schema only hints at via a pattern constraint. It adds nothing for caption, and wait_seconds is only defined in the schema, but the ambiguous parameter is well covered.

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 ('Publishes a carousel of 2–10 images and/or videos') with the distinctive scope markers an agent needs to tell it apart from ig_publish_image, ig_publish_reel, ig_publish_story and ig_publish_container. The multi-item carousel constraint is explicit and unambiguous.

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 operating context: counts as one post against the daily limit, requires IG_ENABLE_WRITES=true, and the exact retry path when videos are still processing. It stops short of naming the single-item siblings as the alternative for non-carousel posts, so the choice between them is left implicit in the tool name.

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