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

Annotations only declare readOnlyHint=false, and the description adds genuinely useful behavior: a two-step challenge round-trip and, critically, that the password is displayed exactly once and must be saved. That one-shot disclosure is the kind of irreversible side effect an agent cannot infer from the schema. It omits failure modes and whether the character is created after the first or second call.

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?

Four short sentences, front-loaded with the fact that this creates a character, then the procedure, then the password caveat. No filler. The telegraphic phrasing ("Пароль создаёт шлюз") is slightly opaque, which costs a point.

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 three-parameter registration tool with no output schema, the description covers the important unknowns: the two-call flow, the one-time password, and the absence of an email requirement. What remains unstated (return shape, duplicate-name handling, challenge expiry) is secondary but non-trivial.

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 100%, so all three parameters are already documented in the schema, including name format rules and the gender enum. The description adds only the operational role of `answer` (the reply to the check-task), which is a marginal gain over the schema baseline.

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?

"Новый персонаж" plus the challenge/password flow makes it clear this is a character-creation (registration) tool, distinct from game_login which it implicitly points to ("сразу после ответа можно входить"). It stops short of naming the sibling explicitly, so it is clear but not maximally differentiated.

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 gives an actionable procedure: the first call returns a check-task and the agent must call again with `answer`. It also removes a likely false prerequisite by stating email and personal data are not needed. It does not say what to do if the name is taken or how long the challenge remains valid, so it stops short of full when/when-not guidance.

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