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

Annotations already establish the safe read-only, idempotent, closed-world profile, and the description goes further by disclosing the return contents (model facts, reasons, shop links, trial availability) and an explicit constraint (no prices, they live on product pages). With no output schema, this return disclosure is genuinely valuable.

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?

Four dense sentences, front-loaded with purpose then domain context then return/constraint notes. No filler sentences, though the Pure/Air explainer and the return list could be tightened slightly.

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 10-parameter, no-output-schema recommendation tool, the description covers purpose, the two required inputs, how to handle unknowns, and what comes back. It omits only minor points (e.g. that lang controls response language), which the schema already documents.

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% with rich enum descriptions, so the baseline is 3. The description does add useful domain framing ('Pure (shop name: Tap Water)', 'Air makes water from humidity'), which helps interpret pref/pipe, but the per-parameter detail is already fully carried by the schema.

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 ('Recommends two Minairal machines') plus the exact scope (best match + second option, or a Pure+Air pair) derived from a customer's situation. It is unmistakably distinct from the retrieval-oriented siblings (get_company_facts, list_locations, search_content).

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 clear context for use (matching the shop quiz 'Which one for me?' rules) and practical input guidance ('Only people and place are required; leave unknown answers out'). It does not name any alternative tool or a when-not-to-use condition, so it stops short of a 5.

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