Compare one product's price across stores

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

Annotations cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds real context beyond them: it makes plain store requests, writes the comparison to local history, and never creates a cart or spends. It also flags result text as untrusted data and warns against following embedded instructions, which is behaviorally important for an open-world scraper. It does not discuss rate limits or failure modes when a store cannot be matched.

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 purpose and starting point, then usage routing, then side effects, then return shape, then the injection warning. Every sentence carries information an agent needs; nothing is redundant with the title or annotations.

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 still describes the return shape (origin product plus offers[] shaped like find_products', with a search_id), so the agent knows what to expect. Combined with the side-effect and untrusted-data notes, nothing needed to call 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 coverage is 100%, so all five parameters are already documented in the schema, establishing a baseline of 3. The description adds only provenance hints for url/product_id (from find_products or search_catalogue) and mentions extra ids like GTIN; it says nothing about results or max_price 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?

States a specific verb and resource ('Find the same product at other stores') and pins the exact starting point (one store URL plus product_id). It explicitly contrasts itself with find_products for open searches, 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?

Gives the trigger condition ('when the shopper wants the best price for a specific product') and names the alternative tool with the condition that selects it ('use find_products for an open search'). It also names the sibling sources for its required inputs (find_products or search_catalogue).

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