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

Annotations only declare readOnlyHint and openWorldHint; the description adds substantial context beyond them — prices are frozen, pricedAt/expiresAt reveal price age and the point at which re-quoting is required, plus the security trait that cartId is a capability not to be published outside the originating conversation. It also explains the display flag's side effect on 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?

Front-loads the core behavior (frozen cart, no re-pricing) before the routing guidance, and every sentence carries distinct, load-bearing information — the freeze semantics, the price-age cue, the when-to-use trigger, and the sibling exclusion. 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?

There is no output schema, so the description compensates by explaining the returned shape at a high level (frozen prices, per-line pricedAt, expiresAt) and the freshness workflow. Combined with the annotations and fully-covered schema, an agent has everything needed to call and interpret this correctly.

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% and both parameters are already documented in-schema, including the cartId capability warning and the display card behavior. The description's pricedAt/expiresAt discussion concerns returned fields rather than parameters, so it adds little parameter-level meaning beyond the schema; the 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?

States a specific verb and resource ('Renvoie le panier') and immediately names the defining scope: the cart as frozen at add-time with no re-pricing on read. It explicitly distinguishes itself from create_cart and update_cart, which 'renvoient déjà le panier complet', so an agent can route without opening sibling schemas.

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?

Gives explicit when-to-use (re-reading a cart later in the conversation, or when the user asks to see it again) and an explicit when-NOT-to-use (right after create_cart or update_cart). It also names the alternative for stale prices (quote_product), so both the trigger and the competing tool are unambiguous.

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