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

Annotations already declare readOnlyHint=true and openWorldHint=true, so no contradiction exists. The description adds useful behavioral context beyond the annotations: it packages what would be two notable_pack calls into one, notes the timeline format, and discloses the $0.08 cost.

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?

Three concise semantic units in one sentence: what it returns, why it is preferable to calling notable_pack twice, and a concrete example. No filler words or redundant restatements.

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 read-only tool with only two required parameters, the description plus the input schema and annotations gives an agent everything needed to call it correctly. It also includes enough comparison-specific context to choose this over notable_pack, and the cost and timeline details remove the main remaining unknowns.

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?

slug_a and slug_b have schema descriptions, and the example reinforces what a slug looks like. However, the description adds nothing about date, peers, or similar, and peers/similar are not described in the schema either, so the 40% schema-description gap is left uncompensated.

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 clear operation: produce side-by-side notable packs for two slugs. It names the resource (notable packs with life_in_days + day_number timelines) and explicitly differentiates itself from notable_pack by noting it replaces two calls. The elon-musk vs steve-jobs example grounds the abstraction.

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?

It explicitly names notable_pack as the alternative and frames compare_lives as the one-call version for comparing two people. It doesn't give formal when-not conditions, but the intended context is clear enough for an agent to decide when to pick this over a single notable_pack call.

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