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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds scope context—every store plus card price protection—and country-based UK filtering, but does not add details like output format, auth needs, or rate limits.

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 short and front-loads the core coverage claim before giving examples and the country note. It repeats the title/brand in the first two sentences, which is mildly redundant, 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?

For a simple, read-only list tool with one optional parameter, no output schema, and rich annotations, the description gives enough context to call it correctly. It could more explicitly state that it returns a list of all supported stores, but the example queries and coverage claim make the function clear.

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?

The single country parameter has 100% schema description coverage, including the GB/UK behavior and default. The description repeats the GB/UK example but does not add meaning beyond what the schema already provides, so the baseline of 3 is appropriate.

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 what the tool covers: "Every store covered, plus card price protection," and gives example queries that clarify the resource. It distinguishes from a single-store tool by emphasizing complete store coverage, though it does not explicitly say "lists all supported stores" in the first sentence.

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 provides concrete usage contexts: requests like "which stores give you money back if the price drops?" or "does my credit card have price protection?". It does not name an alternative sibling tool or state when not to use it, so it falls short of a full 5.

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