WEM Price Compare

Find the lowest listed price

find_lowest_price

Read-only

Find the single lowest-priced product matching the stated constraints. Ranks on price, adjusted for the priorities the caller states (rating, shipping) — never on WEM commission. Use when the user wants a recommendation rather than a list. Candidates are filtered to plausible matches for the query first, so a cheap accessory cannot be returned as the cheapest way to buy the product itself; recommendation may be null with a reason when nothing matched confidently, and that must be reported as "no confident match" rather than softened into a suggestion. recommendation.verified marks an offer whose identity WEM has resolved rather than inferred.

Input Schema

TableJSON Schema

Name	Required	Description
`query`	Yes	What to search for
`max_price`	No	Budget cap (GBP)
`priorities`	No	What matters most (in order of importance)

Output Schema

TableJSON Schema

Name	Required	Description
`score`	No	Internal ranking score. Not a price and not a rating — do not quote it.
`reason`	Yes	Why this was picked, or why nothing was.
`filtered`	No	Withheld candidates tallied by reason (e.g. accessories, wrong model). Report this count rather than implying the search was exhaustive.
`disclosure`	No	Affiliate disclosure to relay once per answer. Outbound links are tracked at no extra cost to the buyer.
`alternatives`	No	Up to three runners-up.
`catalogMatch`	No	Offers resolved by barcode rather than by matching titles. When present, prefer these and cite their prices over anything in `products`.
`recommendation`	Yes	The single lowest-priced plausible match, or null when nothing matched confidently.
`liveSearchSkipped`	No	True when a catalogue hit answered the question without spending retailer API quota.

TDQS

A4.7/5.0

Behavior5/5

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

Beyond the readOnlyHint, the description discloses key behaviors: ranking is never on WEM commission, candidates are pre-filtered for plausibility, null recommendations come with a reason and must be reported honestly, and the `verified` field indicates identity resolution. These add substantial transparency beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is dense but every sentence earns its place: purpose, ranking rule, usage directive, filtering behavior, null handling, and verified flag. It is well-structured and front-loaded, with no filler or repetition.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the output schema exists, the description covers all essential operational aspects: what it returns, when it may return null, how to interpret `verified`, and key filtering logic. It leaves no critical gaps for an agent to make correct invocation or response handling.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema descriptions already cover all three parameters fully (100% coverage). The description adds a little context (e.g., priorities may include 'rating, shipping' and ranking adjusts to them), but it does not materially change or deepen parameter understanding beyond the schema. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific, unambiguous purpose: 'Find the single lowest-priced product matching the stated constraints.' It distinguishes itself from list-returning siblings by noting 'Use when the user wants a recommendation rather than a list' and clarifies the ranking basis is never WEM commission, making it distinct from other search/compare tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states when to use: 'Use when the user wants a recommendation rather than a list.' It also provides important usage caveats, such as candidates being filtered to plausible matches to prevent cheap accessories from being returned as the product, and how to handle null recommendations ('must be reported as "no confident match"').

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

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TDQS

A4.3/5.0

Disambiguation4/5

Each tool targets a distinct action: searching, semantic searching, retrieving categories or product details, comparing offers, comparing products, finding a single lowest price, and verifying a claim. The only mild ambiguity is between search_products and semantic_search, and between compare_offers and find_lowest_price, but the descriptions provide enough separation for an agent to choose correctly.

Naming Consistency4/5

Most tools follow a clear verb_noun pattern such as compare_offers, get_product, search_products, and verify_offer. The main deviation is semantic_search, which is adjective_noun rather than verb_noun, making it the one inconsistent name in an otherwise predictable set.

Tool Count5/5

Eight tools is a well-scoped size for a price-comparison server. Each tool covers a meaningful part of the workflow without redundancy or unnecessary breadth.

Completeness4/5

The toolset covers product discovery, category browsing, detailed product retrieval, multi-offer comparison, side-by-side product comparison, lowest-price recommendation, and price-claim verification. The main gap is the lack of a dedicated price-history tool, even though a 90-day price low is referenced in compare_offers, but this is not a blocking omission for the core comparison workflow.

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