get_listing

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

Annotations already declare readOnlyHint and openWorldHint, so the description needn't restate safety. It adds genuinely non-obvious behavior: legacy ids still resolve, meaning the returned record may be stale and `posted_at` should be inspected — a caveat an agent could not derive from the structured fields.

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 tight sentences, front-loaded with the action and the returned payload, with the staleness caveat placed last where it belongs. No filler or restatement of the tool name.

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?

An output schema exists, so enumerating return fields is a bonus rather than a necessity, and the stale-id behavior is covered. What's missing is only edge-case handling (invalid/removed ids, how precise the seller location is) — minor for a single-record fetch.

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% and already explains where listing_id comes from (search_listings `id` or the /aanbod/<id>/ number), so the baseline is 3. The description adds the extra semantic that an id need not be current, which changes how an agent should interpret and validate the argument.

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 ("Open one advertisement") and enumerates exactly what the record contains — description, condition, warranty, delivery/payment, photos, seller info. The singular "one" implicitly contrasts with search_listings, but no sibling is named, so an agent must infer the split.

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: this is the detail fetch for an item found via search_listings, and the id-source hint lives in the schema rather than the description. The closing note about old ids is a data-freshness caveat rather than explicit when/when-not guidance or a named alternative.

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