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

Annotations already cover the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true), and the description adds real value on top: carousels attach all slides at once, and the operation is 'Free' (no credit cost). It doesn't say whether an attached visual replaces an existing one, which is the main remaining behavioral unknown.

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 short sentences, front-loaded with the action and its prerequisite chain, with the carousel and cost facts compactly appended. Nothing is redundant with the name or 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 no-output-schema mutation with full annotation coverage and 100% schema descriptions, the description supplies the workflow context an agent needs: where job_id and post_id come from, the completion gate, and the carousel/cost behavior.

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 baseline is 3, but the description adds a meaningful constraint beyond the schema: the job_id must be one that get_job reports as completed, not merely created. The user_goal parameter is left entirely to the schema.

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?

Specific verb and resource ('Put a finished visual ... on a planned post'), and the provenance chain (job_id from create_visual, post from get_calendar) implicitly separates it from sibling attach tools like attach_library_media_to_post and attach_video_to_post. It does not name a sibling explicitly, so it stops short of a 5.

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?

The description gives a clear precondition gate: the job must be finished, confirmed via get_job, and the post must be an existing one from get_calendar. It does not state when NOT to use this (e.g. drafts vs scheduled posts, or what to do if the post already has a visual), so no explicit exclusions.

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