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

With no annotations, the description carries the behavioral burden. It discloses the max-3 cap and that results are paid placements marked as ads, which is material for an agent deciding whether to surface them. It does not cover return format or error behavior, but for a simple zero-parameter read tool this is adequate.

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 with no filler: the core action and limit come first, followed by a clarifying disclosure about the ad nature. Every clause earns its place and the information is front-loaded.

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 zero-parameter, no-annotation, simple list tool, the description is complete: it tells the agent what is returned (featured services), the scope (site-wide), the count cap (max 3), and the key semantic detail (paid placements marked as ads). No essential information is missing for correct invocation.

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?

There are zero parameters, so the schema already fully covers everything and the baseline is 4. The description adds useful context about scope and result nature (site-wide, max 3, paid ads), which reinforces what an agent should expect without needing parameter-level detail.

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?

The description states a specific verb and resource: retrieve site-wide featured/promoted services. The qualifiers 'site-wide' and 'max 3' clearly differentiate it from siblings like get_service (single service) and search_services (search all), so an agent can select it without ambiguity.

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 context of paid placements and the max-3 limit implies when to call it (when the agent needs featured/promoted services), but it does not explicitly say when to prefer an alternative or mention exclusion criteria. It gives enough context to infer usage, though without direct alternative routing.

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