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

Annotations already declare read-only and non-destructive behavior. The description adds meaningful behavioral context: the result is non-deterministic and differs per request, which is essential for an agent to manage user expectations. It does not cover response shape or potential rate limits, but the key random behavior is clearly disclosed.

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?

Every sentence earns its place: first states the behavior, then routes to detail and daily alternatives, then cites concrete use cases. It is concise, front-loaded, and free of fluff.

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 tool with no required parameters and read-only annotations, the description is nearly complete. Since there is no output schema, it could plausibly describe the payload shape beyond 'discovery teaser,' but the purpose and alternatives are clear enough for safe 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?

the parameter schema covers both parameters (lang and compact) with full descriptions and examples, so the description does not need to explain them. The description adds no additional parameter-specific insight, so it stays at the baseline for high schema coverage.

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 specifies a distinct action ('Get a randomly selected healing crystal'), a clear resource, and a specific purpose ('discovery teaser'). It also differentiates itself from sibling tools by referencing the detail endpoint and the deterministic daily endpoint.

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 explicitly tells the agent when to use this tool versus alternatives: 'Use /crystals/{id} detail endpoint for complete properties' and 'For a deterministic daily crystal... use /daily endpoint instead.' It also lists relevant use cases, making selection unambiguous.

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