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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description adds genuinely useful behavior beyond that: it discloses that ALL variants are returned and enumerates the variant fields plus sizes and description, compensating for the missing output schema. It does not cover error handling for a bad handle or payload size.

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 zero filler, front-loaded with the primary payload (every variant of one product) and using parentheticals only to enumerate returned fields. Nothing could be cut without losing 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?

For a one-parameter read tool with no output schema, the description covers purpose, input sourcing, and return contents thoroughly. The only omission is failure behavior for an invalid or stale handle, which is a minor gap for this complexity.

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 handle with an example, so the baseline would be 3. The description adds provenance the schema lacks — handles come from search_catalog or a knobs.co/products/<handle> URL — which is real added meaning for obtaining a valid value.

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 (get one product by handle) and immediately scopes the return to every variant with the concrete fields returned. It names search_catalog as the source of handles and even the URL path, so an agent can distinguish it from the search/list siblings without opening the schema.

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?

Gives clear context on how to obtain the required handle ('from search_catalog or a knobs.co/products/<handle> URL'), which implicitly routes the agent to search_catalog first. It does not explicitly say when not to use it or how it relates to sizing_guide/store_info, so no exclusion rules.

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