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

It discloses key behavioral traits beyond annotations: lesson always goes to the end of the module, unknown blocks are discarded, markup is cleaned, allowed block types are listed, and the document format is Editor.js. This is substantial behavioral context that annotations (only booleans) do not provide.

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 and packs a lot of useful detail into a few lines. The Editor.js example is necessary and front-loaded. It could be slightly more structured with separate notes for the `document` parameter, but it is not bloated.

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?

The output schema exists, and annotation booleans are present. The description covers the key tricky part (`document` format) and mentions where to get a sample (`get_lesson`). It does not cover restrictions on `module_id` or how the lesson kind/test parameter interacts with create_test, but overall 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 0%, so the description must compensate. It thoroughly explains the `document` parameter with a detailed Editor.js example, allowed block types, and test format. Other parameters like module_id, title, kind, is_required, duration_minutes have no descriptions, but their meaning is fairly inferable from names/title; still, the description does not fully cover all param semantics.

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 title states a clear action+resource ('Добавить урок в модуль') and the first sentence says the lesson is appended to the end of the module. The description does not explicitly name sibling update_lesson/create_module, but the resource and placement are clear enough. It loses a point because the tool name and title are nearly identical in meaning, and it does not differentiate the action from update_lesson or create_test in the text.

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 is for creating a lesson and places it at the end of a module; it also mentions 'Образец готового документа отдаёт get_lesson' (a sample document is returned by get_lesson), which informs the agent where to learn more. However, it does not explicitly say when to use this tool versus update_lesson or create_test, nor when not to use it.

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