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

Annotations already declare readOnlyHint=true and idempotentHint=true, which covers safety and idempotency. The description adds valuable context: the calculation is free, but full sphere interpretations are a paid product—the tool only returns a link. This disclosure of limitations is beyond what annotations provide and helps set agent expectations about outputs.

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 two sentences, front-loaded with the core purpose (what it calculates) and then a concise note about pricing and output. Every sentence contributes necessary information: the first defines the output, the second explains the free/paid boundary and that a link is provided. No redundant or fluff content.

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 the tool has no output schema and moderate complexity, the description adequately conveys what the tool returns (arcana with names at key points) and the link for paid texts. It doesn't specify response format or link details, but for a calculation tool with annotations and clear schema, it is sufficiently complete. Minor gap: does not state what happens with invalid dates or error handling, but that's not critical.

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 input schema already covers 100% of parameters with descriptions, including date format and locale default. The description does not add any additional semantic meaning beyond what the schema provides. It mentions 'по дате рождения' but that's inherent to the tool's purpose, not new parameter detail. Baseline 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 clearly states the tool calculates 'Матрица судьбы' (Matrix of Fate) from a birth date, listing output types (arcana at key points like personal portrait, destiny, money, love). This specific verb+resource distinguishes it from siblings like calculate_pythagoras, and the purpose is unambiguous.

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 does not explicitly state when to use this tool versus alternatives, nor provide exclusions. It implicitly differentiates itself by naming the Matrix of Fate, but there is no direct guidance on choosing this over calculate_pythagoras or other sibling tools. The context is clear enough, but the explicit when/when-not is missing.

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