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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds behavior beyond that: only "upcoming" items are returned, and it discloses the per-item return shape (id, date, format, platforms, title, hook, brief, status) even though there is no output schema. Ordering and behavior past the limit are not stated.

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, front-loaded with the resource and scope, then the follow-on actions. The field enumeration is dense but earns its place because no output schema exists; nothing is padded.

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 one-parameter read tool with annotations covering safety, the description covers what is returned and how to consume the results, which is the main gap a missing output schema would leave. Remaining omissions (ordering, pagination beyond the limit, empty-plan behavior) are minor.

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?

There is a single optional parameter and the schema documents it fully ("How many items to return, default 50", min 1, max 100). The description adds nothing about limit, so it neither compensates nor needs to — baseline 3 applies when schema coverage is 100%.

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?

"Upcoming items of the content plan Postmately built from the brand profile" names the resource and narrows scope to future-dated plan items, then enumerates the fields each item carries. An agent can tell this apart from list_posts/list_media, though the listing verb itself is only implied by the name/title rather than stated in the description.

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 second sentence gives concrete downstream routing: pass an item id to make_video as planItemId, or use the item's hook with make_carousel. That is real when-to-use guidance tied to named siblings, but it offers no exclusions (e.g., how to get past or non-plan posts, or what to do if the plan is empty).

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