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

The readOnlyHint annotation already establishes the safe, non-destructive nature of the call. The description adds useful context that the output is day-by-day available inventory and can span one or many items, but it does not describe return format, date-range limits, pagination, or other operational constraints.

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?

The description is front-loaded with the core purpose, then gives the key scoping modes and a practical use case. It is compact and each sentence contributes to selection or invocation without wasted wording.

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 read-only availability calendar with full parameter schema coverage and no output schema, the description is nearly complete: it explains the returned concept and supported scopes. It could be slightly stronger by noting expected response structure or any range limits, but no critical invocation detail 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 coverage is 100%, so the schema already documents all four parameters and supported date formats. The description adds relational meaning by clarifying that item_ids with a single id queries one item's calendar, several ids query them together, and category_id is an alternative scope — useful semantics beyond the schema text.

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?

The description states a specific verb and resource: retrieving a day-by-day availability calendar over a date range. It distinguishes supported scopes — single item, multiple items, or a whole category — so the agent can identify it apart from sibling tools like list_items or get_item.

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?

It gives a clear use case: answering 'which days next month still have space?' and explains the scoping options. It does not name when not to use it or point to an alternative tool, so it stops short of full when/when-not guidance.

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