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

Annotations already declare read-only, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the 50-item cap and the fact that unknown ids are skipped with an info message rather than failing. It doesn't explain ordering or whether the info message is structured, but it exceeds the annotation baseline.

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 compact sentences with no filler; the cap and accepted formats are front-loaded and the unknown-id behavior follows. Every clause earns its place.

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 read-only lookup with an output schema available elsewhere, the description covers entry formats and the miss behavior. The gap is the unexplained meta and catalog parameters, which affect invocation and are undocumented in both schema and description.

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 0% and the schema only names ids/meta/catalog with no semantics, so the description carries the burden. It usefully documents the accepted id formats ('ittems:<merchant>:<id>', '<merchant>/<slug>', or SKU), which is essential. However, it says nothing about meta or catalog, so two of three parameters remain unexplained.

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 ('Fetch') and resource ('products by id'), and distinguishes itself from siblings like get_product and search_catalog by being a bulk id-based lookup with an explicit cap of 50. The name, title, and description align.

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?

Usage is implied: use this when you already have ids/SKUs to resolve. But it never explicitly contrasts with get_product (single product) or search_catalog (query-based discovery), which are the obvious alternatives, so the agent must infer the selection rule.

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