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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the description adds useful context beyond them: the 24h data-delay on price drops (critical staleness information), the free-tier framing, and the upsell path. It doesn't cover pagination or result-size limits, but the delay disclosure is genuinely valuable.

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 'FREE.' lead is front-loaded and the content list is dense but every clause conveys distinct information. The single long opening sentence is slightly overloaded, but no sentence is wasted.

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?

With no output schema and no parameters, the description must convey what comes back, and it enumerates the return contents reasonably well. It could be more explicit about the shape/size of the payload, but an agent has enough to decide to call it.

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?

Zero parameters, so there is nothing to disambiguate and the baseline applies. The description correctly implies a no-argument call by describing a fixed aggregate snapshot.

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?

Names a specific resource (e-commerce index over 180+ Shopify stores) and enumerates the exact contents: store/product/variant counts, last crawl time, 24h-delayed price drops, and top discounts. It clearly separates itself from ecom_product, though it does not distinguish itself from nearby siblings like ecom_catalog, ecom_snapshot, or ecom_changes.

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?

Explicitly routes product-level lookups to ecom_product ($0.01), giving a concrete alternative and the condition that selects it. It offers no guidance on when to prefer this teaser over the other ecom_* index tools, so the routing is only partial.

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