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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description still adds real behavioral value by disclosing that the list is derived (planned dinners minus on-hand inventory) rather than a stored, user-maintained list, which explains why it may change as the plan or inventory changes.

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, no filler, with the primary behavior first and the cross-references second. Every clause carries information an agent needs to pick and call the tool.

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?

With no output schema, the description compensates by explaining what the list is composed of, which is the key unknown for a read tool. It does not describe the shape of individual list entries or how quantities/units appear, a minor gap for a single-optional-parameter tool.

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% and the weekStart property already documents the ISO Monday format and the omit-for-current-week default. The description restates the same semantics without adding format, timezone, or edge-case detail, so the schema is doing the heavy lifting.

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?

"Read the shopping list" gives a specific verb plus resource, and the clause "the week's dinners minus what is at home" explains exactly what the returned list represents. It also names the adjacent sibling get_shopping_guide, so an agent can distinguish this from the guide/cart tooling.

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 states the default branch explicitly ("or the current week without one") and routes the agent to get_shopping_guide and the shop_online prompt for the cart step. It gives no exclusion guidance for the other shopping siblings (add_shopping_item, check_shopping_item, remove_shopping_item), so the routing picture is clear but not exhaustive.

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