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

Annotations already declare readOnly/idempotent/closed-world, so the bar is lower, and the description adds real value beyond them: data provenance ('company-provided, not part of the CC BY dataset') and a neutrality guarantee ('sponsorship never changes ordering') that an agent could not infer from structured fields.

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-loads the scope, then lists fields, then appends provenance and ranking caveats — all in three tight clauses with no filler. Slightly dense but 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?

With no output schema, the description compensates by naming the return fields and the metadata envelope (provided_by, last_confirmed_at, sponsored). For a read-only single-record lookup this is close to complete; only pagination/error behavior is unaddressed, which is largely irrelevant here.

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?

Single slug parameter with 100% schema coverage, where the schema already explains 'Product slug from its URL.' The description adds no format or sourcing detail 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?

States a specific verb and resource ('Full public listing for one product by slug') and enumerates the returned fields, which cleanly separates it from the sibling search_products (retrieval by slug vs. query). An agent can tell what it gets without opening the schema.

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 only implied: 'by slug' signals the input needed, and the sibling search_products is the natural alternative, but the description never says when to prefer this over searching. No explicit exclusions or prerequisites are given.

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