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

Adds substantial context beyond annotations: it discloses the return payload shape (ranked products, every offer, seller, condition, price-check date) and, importantly, the asynchronous behavior — a missing comparison is started and returns status 'pending' with retry_after_seconds, resolvable ~60s later. This also explains why readOnlyHint is false despite the read-like framing.

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-loaded with the core purpose, then layered with return detail and the pending/retry caveat. Information density is high with no filler, though the async clause is somewhat dense and could be tightened.

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 carries the full burden and does so well: it describes the returned fields, the merchant coverage, and the pending-status edge case with a retry hint. Nothing essential for a correct call 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 100%, so the schema already documents query, limit and max_price. The description mirrors the query concept (category or specific model) but adds no syntax, format or currency nuance beyond what the schema provides; baseline 3 is appropriate.

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 — compares product prices across merchants — with geographic scoping (comparr.fr / comparr.co) that clearly separates it from sibling lookups like get_product and get_price_history. An agent can identify its role without opening the 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?

The description conveys when the tool is useful (comparing a category or a specific model across merchants), but never explicitly names the alternatives (get_product, get_price_history, get_deals) or states when NOT to use it. Usage is implied rather than prescribed.

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