Compare Prices Across Russian Marketplaces

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

Annotations already set readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, but the description adds substantial context beyond that: cheapest excludes Yandex subscription price, source_outcomes indicates partial results, titles are matched loosely, and individual source failures do not raise errors. This is exactly the kind of behavior an agent needs to interpret output correctly.

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 long but every section earns its place: clear purpose, explicit usage guidance, two important output caveats, a note on matching behavior, and structured return/error format. It is front-loaded with the essential purpose and uses formatting (sections, em-dashes) to make scanning easy. No 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?

For a tool with three parameters, complex behavior (concurrent queries, partial failures, subscription prices), and a rich output schema, this description covers all necessary aspects: what it does, when to use it, how to interpret results, what the return structure looks like, and how errors are handled. It is complete enough for an agent to invoke and use the results 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?

The input schema covers all parameters with descriptions, so the baseline is 3. The description adds some relevant context about loose title matching and 'in Russian' for the query parameter, but it does not significantly extend the schema's parameter explanations. It meets the baseline without exceeding it.

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 opens with a specific verb and resource: 'Price one product across every configured Russian marketplace at once.' It clearly distinguishes itself from per-marketplace search tools by emphasizing the concurrent comparison and ranking, so an agent immediately knows what this tool uniquely does.

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?

The description explicitly states when to use this tool: 'This is the tool for "where is X cheapest"' and contrasts it with the slower alternative of running per-marketplace search tools one at a time. It also implicitly tells the agent when NOT to use it (when you need a single marketplace's detailed results, use those sibling tools).

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