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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds inventory/shelf context (sale badge, stock level, availability) that is not conveyed by the annotations, but it says nothing about auth, store scoping requirements, or locale sensitivity of pricing.

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 with no filler, and the store scoping qualifier comes before the field list. The trailing enumeration of returned fields is verbose, especially since an output schema already exists, but nothing is wasted in a misleading way.

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?

Output values are covered by the existing output schema and safety by annotations, so those are fine. The critical gap is the five required parameters with no descriptions anywhere, which leaves the agent unable to assemble a valid call without external discovery.

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?

All five parameters have 0% schema description coverage, so the description must carry the burden and it does not. It never explains the relationship between shop_id, store_slug, retailer_location_id, product_id, and postal_code, so an agent cannot infer where these identifiers come from.

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 resource (Instacart product detail) scoped to a specific store, and enumerates the returned fields (name, size, brand, pricing, availability, stock, dietary labels, nutrition). Its contrast with instacart_search is implied by the sibling naming but never stated, so it stops 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?

There is no when-to-use guidance at all. Nothing tells the agent to call search first to obtain product_id, or which of instacart_search/instacart_stores/instacart_departments to use to harvest the five required identifiers.

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