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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds useful output-shape context ('plain-language differences', 'rank, score and verdict'), but says nothing about behavior when a product is missing from rankings or when the two products don't share any ranking.

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?

A single dense sentence that front-loads the core output ('two products side by side') and then enumerates what's returned. No filler, nothing redundant.

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?

A low-complexity two-param read tool with full annotations and no output schema. The description conveys the response shape well enough to call correctly. Minor gap: no signal on behavior when rankings are missing or when the slugs don't resolve.

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 100% and both params are documented with pattern and 'product slug' semantics. The description adds no parameter-level detail beyond the schema. Baseline 3 applies.

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 ('compare') and resource ('products') with concrete scope: 'facts, plain-language differences, and the rank, score and verdict each gets in every ranking both appear in.' This content-level specificity distinguishes it from get_product (single lookup) and find_alternatives without needing to name them.

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 scope ('every ranking both appear in') implies this is for pairwise comparison, but it never says when to prefer compare_products over calling get_product twice or find_alternatives. No explicit when/when-not or alternative named.

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