Megamarket Product Card

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

The description goes well beyond the readOnlyHint/idempotentHint annotations by specifying the exact response envelope (MegamarketCardResponse fields) and detailed error modes including BadRequestError, NotFoundError, TransportDownError, and ParserDriftError. No contradiction with annotations exists.

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 compact, front-loaded with the core purpose, and uses clear Return Format / Error Format sections that add useful structure without redundancy. Every sentence contributes relevant information.

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 single-parameter, read-only card lookup, the description together with the schema and annotations is complete: it states what is returned, how failures surface, and what input is expected. Search and discovery concerns belong to sibling tools, so their absence is not a gap.

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 schema already fully documents the single parameter with 100% coverage ('Goods id or megamarket.ru product URL'), so the description adds no additional parameter-level meaning. Baseline 3 is appropriate given full schema coverage.

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 a specific verb and resource: 'Fetch one Megamarket product card.' The word 'one' clearly distinguishes this from the sibling megamarket_search tool, and the Megamarket qualifier distinguishes it from the many other marketplace card tools.

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 context is implied rather than explicit: the tool is for fetching a single known Megamarket product card, so an agent can infer it should be used when it already has an item id or URL. However, it does not explicitly say when not to use it or direct the agent to megamarket_search for discovery.

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