Что этот сервер умеет и что скрыто

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

Annotations already provide readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds genuinely useful behavior beyond annotations: it makes no API call to Metrika and requires no token, preventing the agent from assuming the token/auth obligations that sibling data tools carry.

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?

Three sentences, each earning its place: what it lists, when to invoke it, and the behavioral caveat about no API/token. The core function is front-loaded.

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 zero-parameter tool with no output schema, the description covers purpose, invocation triggers, and behavior. It also describes the return content (declared tools, hidden tools, enablement instructions), which substitutes for the missing output schema.

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?

Zero parameters, so the schema covers 100% and the baseline of 4 applies. The description confirms the tool is callable without arguments and states what the empty call yields.

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 verb and resource: it lists Yandex Metrika tools with their current visibility status, profile-hidden tools, and enablement instructions. It is clearly distinguished from all 10 siblings (stat_*, counter_*, goal_*, segment_* data tools) because it is a meta-tool about the server's own catalog, not a data-access tool.

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?

Gives explicit trigger conditions: call when the needed Metrika tool is not visible in the list or when the user asks what the server can do. It doesn't name specific sibling alternatives, and the when-not is only implicit (use it for discovery, not data operations), so it stops short of a full 5.

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