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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the exact return shape `{results:[{id,title,url}]}` and the fact that `id` is a product handle usable downstream — valuable because no output schema exists. It omits result count, ranking/fuzzy-match behavior, and empty-result behavior, keeping it off a 5.

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?

Two short sentences, zero filler, with the search scope front-loaded and the return-shape/`fetch` chaining detail immediately after. 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?

For a one-parameter read-only search with no output schema, the description covers purpose, return structure and the key downstream linkage, which is close to sufficient. The remaining gaps — sibling disambiguation from `search_catalog` and result-count/empty-result expectations — are the only things an agent might still need.

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 single `query` parameter already carries a rich plain-words description with an example. The description adds no syntax, formatting, or query-construction guidance beyond the schema, so the 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?

"Search Knobs.co products" gives a specific verb and a scoped resource, which is far better than a bare name restatement. It stops short of differentiating from the sibling `search_catalog`, which sounds nearly identical, so an agent still can't tell the two apart from the description alone.

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 clause "id is the product handle for fetch" usefully routes the agent to the follow-up tool, which is real usage guidance. However, there is no statement of when to use this versus `search_catalog`, `get_product`, or `ask_sienna`, and no exclusions or prerequisites.

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