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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the description's added value is the result semantics: a live Amazon price per item and a BUY call only when the price is a genuine low against its own history, otherwise none. That is meaningful domain behavior beyond the annotations. It stops short of stating result ordering or empty-result behavior beyond "broaden".

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 what the tool searches and what a result carries, then lists filters compactly. The parenthetical about the BUY call is long and slightly interrupts the flow, but every sentence carries information and nothing is redundant with the schema.

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 takes on the burden of describing returns (up to limit products with price, verdict and a one-line note) and does so adequately. Missing pieces are result ordering/relevance ranking and any indication of how many filters combine, which an agent might want for a 7-parameter search.

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 coverage is 100%, so the baseline is 3, but the description adds genuine meaning: it glosses "slot" as "the role a product plays in a setup" and specifies that free-text matches name/brand/notes, which the schema does not say. It also frames the price parameters as a band and confirms on-sale maps to verdict=buy, closing the gap between the enum-ish naming and actual behavior.

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?

Opens with a specific verb+resource ("Search the espresso gear this site tracks") and immediately scopes what a result contains. It is clearly distinguishable from siblings get_product (single lookup), list_slots (enumeration) and watch_price (subscription), so an agent can route correctly without opening a 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?

Explicitly instructs iterative use ("Call it more than once with different filters; broaden if a search returns nothing"), which is real operational guidance for a filter-heavy search tool. It does not, however, name when to prefer get_product or list_slots instead, so the sibling boundary is left to inference.

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