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

The annotations already declare readOnly, idempotent, and non-destructive behavior, and the description adds substantial behavioral context beyond them: input order is preserved, Ranked-operated products are partitioned into a separate unranked block, are flagged with operated_by_ranked=true, and are never ordered above others. The note that evidence tier indicates provenance rather than quality is also meaningful and non-obvious.

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?

The description is compact and information-dense. Every sentence earns its place: core operation, count constraint, comparison dimensions, ordering behavior, operated-by-Ranked handling, and evidence-tier semantics. There is no filler or redundancy.

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?

The tool has a single parameter and no output schema, but the description covers the essential invocation semantics and the important behavioral quirks, including the special handling of Ranked-operated products. The annotations cover safety and idempotency, so the overall picture is complete enough for an agent 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?

The schema has no parameter descriptions and 0% coverage, so the description is the sole source of semantic meaning. It explains that the names parameter accepts 2-5 named products or services, specifies the comparison dimensions, and clarifies that the order of the names array controls output row order. This fully compensates for the bare schema.

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 uses a specific verb ('Compare') and a specific resource ('products or services on Nigeria-usability'), and it names the four concrete criteria (naira pricing, card acceptance, local entity, geo-restriction). It also differentiates itself from ranking tools by explicitly stating that rows are returned in the given order and not ranked.

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 description gives clear context: use this tool when you need to compare 2-5 named products or services on Nigeria-usability. It does not explicitly name sibling tools as alternatives, and it lacks an explicit when-not-to-use statement, but the trigger conditions are clear and no alternatives are wrongly implied.

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