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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safe-read profile is covered structurally. The description adds that the response includes price and an orderability flag, which is useful behavioural detail, but says nothing about auth needs, rate limits, or behaviour for unknown/invalid product ids.

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 tight sentences: the first front-loads what is returned, the second gives the follow-up action. No filler, no repetition of the title, and the highest-value information leads.

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 correctly compensates by naming the returned fields, and it provides a routing hint to add_line. The only real gap is that the single input parameter is never described, which matters at 0% schema coverage.

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?

There is one required input, product_id, and schema description coverage is 0%, so the description must carry the burden. It only obliquely says 'of a product' and instead highlights combination_id, which is an output field, not an input — an agent gets no confirmation of what to pass in.

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 states a specific resource and enumerates the returned fields (combination_id, price, orderable flag), so an agent knows this is a stock/availability lookup for a product's size-colour variants. It is clear, but it never explicitly contrasts itself with close siblings like get_product or get_size_guide.

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?

'Pass combination_id to add_line' gives a concrete downstream workflow hint, implying this is the prerequisite lookup before adding a line item. However, it never states when to use this tool instead of get_product or search_catalogue, so the selection guidance is only implied.

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