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

The annotations already establish read-only, idempotent, non-destructive, closed-world behavior, so the description is not obligated to restate safety. It does add genuinely new behavioral context by disclosing the ranking logic behind the returned list (editor's picks, then makers' declarations, then relevance/upvotes), which an agent cannot derive from structured fields. It says nothing about pagination behavior or what happens when a slug has no alternatives.

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 sentence with no filler, front-loaded with the core action and resource, then the ordering rule. Every clause carries information.

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?

An output schema exists, so return value structure need not be explained, and both parameters are covered by the schema. The one material gap is the absence of any note on result-set size or pagination relative to the limit parameter, but overall the definition is sufficient to call the 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?

Schema coverage is 100%, so both parameters are already documented in structured data, making 3 the baseline. The description reinforces that the slug identifies a single product but adds no new constraint or format guidance, and it does not mention the limit parameter or its default/max.

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 names a specific verb and resource ('List the alternatives to one product') and pins the identifier to a slug, so the operation is unambiguous. It does not explicitly contrast itself with near-neighbors such as compare_products or get_product, so it stops short of full sibling differentiation.

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 only implied: an agent can infer this is the tool for finding substitutes for a single product. There is no statement of when to prefer it over compare_products (multi-product comparison) or search_products, and no preconditions such as the slug needing to exist.

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