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

Annotations already establish it as a read-only, non-destructive, open-world lookup, but the description adds real behavior: it answers from published terms and never waits on the item count, and it explains that a null catalogSize/catalogVisibility has two non-interchangeable meanings. That null-handling contract is the kind of detail annotations cannot convey. It stops short of describing pagination or freshness/latency of the published terms.

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?

Front-loaded with the purpose, then usage, then the caveat about nulls; every sentence carries information. It is somewhat dense and the null discussion runs long, but nothing is filler.

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?

No output schema exists, so the description carries the return-value burden and does so: it names the returned fields, their provenance, and the semantics of null catalog fields. An agent has enough to call and interpret the result 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?

With 100% schema coverage and a single required parameter, the schema already documents service_slug including the 'shufersal-online' example. The description's 'take the slug from a plan's serviceSlug' restates the schema rather than adding new syntax or constraints, so 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?

States a specific verb and resource ('the full published terms for a single online storefront') and enumerates the payload (fee bands, minimum order, service area, provenance), which cleanly separates it from list_delivery_options and optimize_delivery.

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 two concrete use cases (explaining a deliveryFee from an optimize_delivery plan, answering the free-delivery threshold question), names the alternative for counts (list_delivery_options), and warns against the wrong inference from a null.

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