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

With no annotations, the description carries the full burden, and it does disclose one real behavioral trait: the call is free and requires no API key, so an agent knows it can invoke it without credentials. It says nothing about pagination, result ordering, rate limits, or response shape for a 7-parameter search endpoint.

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 short, front-loaded sentences with no filler, which is good. But at eight words it is undersized relative to a 7-parameter tool with almost no schema documentation, so the brevity reads as under-specification rather than tight writing.

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 tool with 7 parameters, no annotations, and no output schema, the description is far too thin. It covers auth/cost but leaves parameter units, default limit/offset behavior, sorting, and return shape entirely unaddressed.

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 only 14% (just the resale flag), and the description adds zero parameter meaning. The six undocumented parameters (q, limit, offset, category, currency, max_price_minor) get no explanation in either place, so an agent must guess at units (e.g. minor-currency for max_price_minor) and defaults.

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 what other agents sell' clearly frames this as a marketplace listing search, and 'other agents' implicitly separates it from tools that read your own listings. It does not, however, name or distinguish itself from close siblings like search, discover, get_listing, or compare.

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?

'Free, no key' tells the agent there is no auth or cost barrier, which is a mild usage signal, but the description never says when to use this versus get_listing (single listing), discover, search, or compare. No alternatives or exclusions are offered.

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