Avito Item Card

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

The description goes well beyond the provided annotations by documenting the return format in detail, including the important edge case that price_rub is None when no price exists and never 0. It also enumerates the full error taxonomy: BadRequestError, NotFoundError, TransportDownError, and ParserDriftError, giving the agent clear expectations about failure modes.

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 well organized with clear sections for return format and error format. Every sentence carries useful information, and the most important information is front-loaded in the opening sentence.

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 tool with a rich output schema and detailed annotations, the description covers return semantics and error handling thoroughly. Nothing essential is missing for an agent to select and invoke this tool 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?

Schema coverage is 100%, with the parameter description 'Item id, slug path or full avito.ru URL' already capturing the accepted formats. The description reinforces this by mentioning 'by id or URL' and adds no confusion, though it does not need to add much beyond the schema.

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: 'Fetch one Avito listing by id or URL.' This clearly distinguishes the tool from sibling tools like avito_search and avito_seller, which operate on search results or seller pages rather than a single listing card.

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 implies the tool should be used when you already have a listing id, slug, or URL, but it does not explicitly state when to prefer this over avito_search or avito_seller. Usage context is implied rather than spelled out, so guidance is adequate but not thorough.

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