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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so safety is covered. The description adds real behavioral value beyond that: the forecast derives from logged usage with age-typical fallbacks and reads on-hand state recorded via set_inventory, which tells the agent what data drives the result.

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?

One compact sentence with the forecast type front-loaded and the determinative inputs following. The item list is a touch long but each element is informative, and there is 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?

No output schema exists, and the description does disclose the shape of the result (days-remaining per item) plus the fallback behavior when usage data is missing. For a zero-parameter read tool with full annotation coverage this is close to complete, though it could note what happens if nothing is logged at all.

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?

The tool takes zero parameters, so the schema baseline is 4. The description correctly does not invent parameter semantics, and it clarifies the implicit data sources instead.

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 ('days-remaining forecast') and enumerates exactly which categories it covers (nappies, wipes, formula, vitamin D drops, milk). This is clearly distinguishable from sibling tools like set_inventory (which records on-hand) and get_status.

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?

Usage is implied rather than stated: it conveys that this is a forecast request whose inputs come from logged usage and set_inventory, hinting at a prerequisite. But it never explicitly says when to call this vs alternatives like get_status or get_today, and gives no exclusions.

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