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

With no annotations, the description carries full burden, and it is highly transparent. It explains what happens on missing slug ('isError' with text 'Не найдено'), clarifies the semantic of null for first_loan_zero_percent, details the meaning of legal.license_registry_url as a primary source, and adds the attribution requirement for canonical_url. This goes well beyond a basic summary.

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 information-dense; every clause adds a distinct detail about the returned data or behavior. It is front-loaded with the core purpose, then systematically covers data groups, edge cases, routing, and attribution. No filler or repetition is present.

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?

Given there is no output schema, the description thoroughly covers the return value composition: conditions, summary, requirements, commissions, rating, legal data, and actualization date. It also covers error handling, null semantics, a direct registry link, and the relationship to sibling tools. This is sufficient for an agent to call the tool correctly and interpret its output.

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 covers the slug parameter fully with detailed description, including example and source instructions, so the baseline is 3. The tool description adds only the phrase 'по slug', which restates the schema. It does not materially expand parameter semantics beyond the schema, so a 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 opens with a clear verb+resource statement: 'Полная карточка одной МФО по slug' (full card of one MFO by slug). It enumerates the specific data groups returned (conditions, summary, requirements, commissions, rating, legal data, actualization date), which makes the tool's purpose concrete. It also distinguishes itself from siblings by stating that reviews are obtained via get_reviews.

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 tells the agent when this tool is NOT for reviews and routes to get_reviews: 'Отзывы — через get_reviews.' It also instructs the agent to take the slug from list_mfo, search_offers, or get_category and not guess it, which is a direct usage guideline. This is clear and actionable.

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