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

readOnlyHint=true already tells the agent this is a safe read, so the description's added value is mainly the disclosure of returned content (level, challenge/duel/battle availability), useful given there is no output schema. It says nothing about behavior for a non-existent or offline player, rate limits, or whether the data is a snapshot versus live state.

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?

A single front-loaded sentence with no filler, and the key 'player card' framing comes first. It loses a point for the muddled tail 'можно ли вызвать на бой, дуэли, бой', where 'бой' is repeated and the distinction between challenge/duel/battle is left ambiguous.

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 one-parameter read-only lookup with an annotation covering safety and no output schema, the description covers the essentials—what resource, what fields come back. It is still thin on input format for 'login' and on error behavior, which an agent would need before invoking it confidently.

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% and the single 'login' parameter has no description at all. The phrase 'клик по нику' only loosely implies the identifier is a player nickname, and it never clarifies whether it must be an exact login, whether case matters, or whether it can refer to a player other than the caller—so compensation for the coverage gap is minimal.

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?

States a specific resource (player card, the equivalent of clicking a nickname) and enumerates what it exposes: level, whether the player can be challenged, duels, battle. That distinguishes it from siblings like game_status (own state) or game_look (location), though the verb is only implied by the noun phrase rather than written out.

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 'like clicking on a nickname' analogy hints at the use case of inspecting another player, but there is no explicit when-to-use, no indication of what to use instead for one's own profile (game_status), and no prerequisites or failure conditions for unknown logins.

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