search_listings

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

With no annotations, the description carries the full burden and does reasonably well: it discloses defaults (limit 10, distance 1000), cross-parameter constraints (distance_km requires zip_code), pagination shape (next_offset) and the return dict contents. It omits anything about rate limits, error behavior, or result ordering guarantees, which keeps it out of the top band.

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 one-line summary followed by a tight, scannable Args list where each line maps to one parameter; for a 16-parameter tool this is appropriately sized. The 'Returns:' block lightly duplicates the existing output schema, but it is one sentence and does not bloat the definition.

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 return values need not be explained, and the description nonetheless summarizes it. Combined with full per-parameter documentation at zero schema coverage and explicit inter-parameter conditions, an agent has everything needed to call this tool correctly.

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 0%, so the description is the only source of parameter meaning, and it documents all 16 parameters: allowed site values, per-site zip formats ('1016LV' vs '2000'), the five condition enums, seller_type aliases (business/zakelijk, private/particulier), sort_by options, and limit bounds. This is exactly the compensation the low schema coverage demands.

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 ('Search for listings') plus the exact marketplaces (marktplaats.nl, 2dehands.be), which is more specific than a generic search tool. However it never distinguishes itself from sibling search-like tools such as hunt, save_search, or check_saved_search, so an agent must infer that this is the ad-hoc/one-shot search.

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 implied through conditional notes, e.g. 'query: required if no category specified' and 'attribute_ids: use get_category_filters', which is genuinely useful routing. But there is no explicit when-to-use/when-not statement relative to hunt, save_search, or check_saved_search, so guidance is only partial.

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