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

The annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds useful behavioral context by explaining that these are independent price-comparison sites and that each has its own MCP server for deeper category, brand, guide, and toplist questions.

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 a single front-loaded sentence that immediately states what the tool returns. The long parenthetical category list is informative but slightly dense; overall it remains efficient with no redundant sentences.

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 one-parameter list tool with rich annotations and no output schema, the description adequately covers the returned site fields and the role of each site's MCP server. It could be more complete by explicitly routing usage against sibling tools, but it is sufficient for correct invocation.

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 100%, and the single locale parameter is fully documented with enum values and market/language semantics. The description adds no additional meaning about locale filtering, so the schema does the heavy lifting and 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 clearly identifies the resource as the independent price-comparison sites searched by the server and enumerates the returned fields (key, name, coverage, markets, languages, home page, MCP server). It is distinct from the product-search siblings, though it does not explicitly contrast itself with them.

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 implies the tool is for discovering available sites and notes that each site has its own MCP server for deeper questions. However, it does not state when to call list_sites instead of search_products, compare_prices, best_deals, or find_by_code, nor does it say to use it before locale-specific searches.

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