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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description still adds real context: it requires the user's EINI login, and the picks are the cheapest using this week's deals, which tells the agent where the data comes from and why prices look the way they do.

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 dominant sentence front-loads the resource and then lists the returned fields compactly, followed by a short default-behavior clause and a short auth clause. No filler, though the description uses a noun-phrase construction with no explicit verb.

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?

There is no output schema, so the description must carry the return shape, and it does: it enumerates the per-item fields and flags. Combined with the auth requirement and default filtering, an agent has what it needs, with only the absence of sibling-routing guidance as a gap.

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 description coverage is 100%, so both parameters are already fully documented with an example for store and an explicit default for open_only. The description restates the open_only default and adds only slight framing about store-picked products, so baseline 3 applies.

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 the concrete resource (the user's current EINI meal-plan shopping list) and enumerates its content: quantity, chosen store/product, pack price in CHF, and promotion status. That is specific enough to separate it from eini_search_deals, though it never explicitly contrasts itself with a sibling by name.

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?

Use is implied rather than stated: it serves the current meal plan and defaults to unticked items, which hints at the 'what do I still need to buy' scenario. There is no explicit guidance on when to prefer this over eini_search_deals or eini_my_meal_plan, and no exclusions.

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