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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the mutation/idempotency profile is covered. The description adds that this is a reversible toggle keyed by item name, but says nothing about what happens when the item or week does not exist, or whether duplicate names are an issue.

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?

A single front-loaded sentence that pairs each operation with its parameter value, with no filler. It is perhaps slightly dense in that the week scope is omitted rather than misplaced, but nothing needs trimming.

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 simple three-parameter toggle with full schema descriptions, complete annotation coverage, and no output schema, the description covers the essential action and both directions. The only meaningful gap is failure behavior for a missing item or an ambiguous name.

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 both purchased and itemName are already well documented in the schema. The description restates the purchased semantics ('purchased=true / purchased=false') rather than adding new meaning, and never mentions weekStart, which the schema has to carry on its own. Baseline 3 is appropriate.

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 names a specific verb pair ('tick off' / 'put back') and the resource ('shopping list item'), and clarifies it is identified by name. It does not name the nearby siblings (remove_shopping_item, add_shopping_item) to make the distinction explicit, so it lands just 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?

It states the two modes of use (purchased=true to tick off, purchased=false to restore), which implies when to call it. It never addresses alternatives — e.g. that removing an item entirely is remove_shopping_item's job, not this tool's — so the agent must infer that routing.

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