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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds 'Deterministic' and a credit cost, which is useful context, but says nothing about how allowReversed affects the reading or what the draw actually returns.

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?

Extremely tight and front-loaded, with the core action first and scannable metadata tags after. Nothing is wasteful, though the brevity is partly under-specification rather than pure economy.

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?

The output schema exists, so return values need not be described here, and annotations cover safety. Still, for a 5-parameter tool with 40% coverage and no usage routing, the definition leaves an agent without enough to invoke it confidently versus its rune siblings.

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 coverage is only 40%: date, seed, and allowReversed carry no descriptions, and the description adds no meaning for any of them. 'Deterministic' hints that seed matters but never explains its format or role, so it fails to compensate for the documentation gap.

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 ('1-rune draw') and the scope qualifier '1-rune' implicitly separates it from siblings like astroway_runes_three, astroway_runes_nine, and astroway_runes_runes. However, it never names those siblings, so the differentiation is left to inference.

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?

There is no when-to-use guidance, no conditions, and no reference to alternative rune tools. The metadata block (group, endpoint, cost) describes plumbing, not usage selection, so the agent gets no help choosing between this and the three/nine-rune variants.

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