list_items

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the description's real contribution is the aggregation semantics: stock levels are combined across all warehouses, which the annotations cannot express. It does not restate destructive/read-only behavior, and pagination behavior is carried by the schema, so this is a genuine value-add without being exhaustive.

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 short sentences, front-loaded with what the tool returns and scoped immediately, then the alternative. No filler or restated parameter names.

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 an output schema present, return values need not be described, and the description covers scope, contents, use case, and the correct alternative. Nothing an agent needs to invoke this correctly is missing.

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 80%, so the schema already documents cursor, status, page_size, and low_stock_only. The description only implicitly gestures at low_stock_only through the 'running low' example and adds no syntax or defaulting detail beyond the schema, so 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?

Specific verb ('Browse') plus resource ('the merchant's catalogue') with the added scope 'stock levels (all warehouses combined)'. It names the sibling check_availability as the non-overlapping alternative, so an agent can route between the two without opening either schema.

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?

Explicit when-to-use is given ('overviews such as "what is running low?"') along with the alternative for specific SKUs (check_availability), which is strong routing guidance. It does not differentiate from search_items, the other plausibly overlapping sibling, so it falls short of a full when/when-not map.

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