Cheapest offer

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

Annotations already declare readOnly, idempotent, open-world, and non-destructive, so the safety profile is covered. The description adds real value beyond that: it discloses the multi-step search-then-check-every-shop behavior and warns that the matched product name may not be exact, which is important for trusting results. It stops short of stating cost/latency implications of checking multiple candidates.

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 the purpose, with no filler. The return-shape sentence is slightly compressed ('per top match and the overall `cheapest`'), but nothing is wasted.

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?

For a 6-parameter, no-output-schema tool, the description covers purpose, internal search behavior, return shape, and the fuzzy-match caveat. The main remaining gap is that it doesn't quantify that each candidate match costs an extra request, though the schema's candidates description mentions 'one request each'.

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%, so every parameter is already documented, and the baseline is 3. The description reinforces the query semantics ('named in words') and implies the candidates concept via 'top match', but adds nothing about city, condition, min_score, or installment_only beyond what the schema states.

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 uses a specific verb+resource ('Cheapest trustworthy offer for a product named in words') and explains the internal two-step behavior (search, then inspect every shop's offer). It is clear what the tool returns ('best usable offer per top match and the overall cheapest'), though it doesn't explicitly contrast itself with near-neighbors like tb_offers, tb_best_value, or tb_compare.

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?

Usage is only implied: you supply a product 'named in words' and get the cheapest trustworthy offer. There is no explicit when-to-use vs. when-not, and no sibling is named as an alternative for cases like browsing all offers (tb_offers) or comparing specific products (tb_compare). The 'check the matched name' note is a useful caveat but not routing guidance.

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