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

Annotations already cover the safety profile (readOnlyHint, openWorldHint=false), so the bar is lower, and the description usefully adds the exact return payload (price/terms, last checked, country, open source, self-hostable, reviews, positioning) plus the 2-4 cardinality constraint. It omits any note on failure behavior for unknown slugs or rate limits.

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 sentences, front-loaded with the core behavior and the returned fact list, with no filler. The long enumerations are dense but they substitute for a missing output schema, so they earn their place.

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?

With no output schema, the description correctly carries the return-value burden by listing every compared field. Cardinality and required input are covered by the schema, so the only residual gap is the absence of error/edge-case guidance.

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 the schema already documents the slugs array, so the baseline is 3. The description adds genuine value beyond the schema by specifying slug provenance (search_tools, find_alternatives) and that exact names are also accepted.

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+resource (compare two to four listings side by side) and even enumerates the exact fields returned for each listing. It is clearly distinguishable from siblings like get_tool (single lookup) and search_tools (broad search), which the description names as slug sources.

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 by the cardinality and comparison framing, and it tells the agent where slugs come from (search_tools, find_alternatives, or exact names). It never states when to prefer this over get_tool for a single item or when comparison is inappropriate.

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