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

The description discloses several behavioral traits beyond the readOnlyHint annotation: concurrent fan-out, skipping slow/failing stores, weighting of rare vs common words, and the explicit 'No strong match' response with close weak matches. This is rich, non-obvious behavior that materially affects how an agent should interpret results and decide next steps.

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?

The description is moderately sized but every sentence adds information: purpose, fan-out behavior, scoring, failure mode, category guidance, and an example. It front-loads the core purpose and uses a clear paragraph structure. No fluff, though the example could be considered slightly redundant given the schema.

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?

Given the tool's complexity (multi-store fan-out, concurrency, scoring, fallback behavior), the description covers the return format ('results grouped by store with each store's UCP score and evidence'), the no-match case, and the category behavior. It does not detail pagination or output limits beyond maxStores, but the core invocation and expected output are well-covered, especially with a fully described schema.

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%, so the baseline is 3. The description adds value by explaining the fan-out semantics of `category` ('narrows the fan-out to the smaller set of deeply audited stores') and the default/max for `maxStores`, which is already in the schema but reinforced. It also adds a practical example. This exceeds the baseline.

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 specific verb ('Search') and resource ('products across verified UCP stores at once'), and immediately distinguishes itself by describing a fan-out to multiple stores with grouping and UCP scoring. This clearly separates it from siblings like search-catalog (likely single-store) and search-policies (policy search), even without naming them explicitly.

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 gives concrete guidance on when to use it ('most queries') and specifically advises to leave out the `category` parameter for typical use, while noting that category narrows the fan-out. It also explains the no-match fallback and how to proceed ('go to a store you know'). However, it does not explicitly contrast with sibling tools like search-catalog, leaving the choice to inference.

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