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

Annotations already declare readOnlyHint, idempotentHint, closed-world and non-destructive, so safety is covered. The description adds two genuinely useful facts beyond the annotations: that the draw is deterministic (implying the seed makes results reproducible) and that it costs 10 credits (Tier 1). It does not explain reversal handling or what the draw returns, but with annotations carrying the safety profile a 3 is appropriate.

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?

Front-loaded with the core capability on line one, followed by two bracketed metadata lines. Nothing is wasted, though the brevity tips into under-specification rather than tightness.

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?

With an output schema present, return values need not be described, but the five parameters at 40% coverage plus zero usage guidance leave real gaps. An agent cannot tell what seed and date do, how allowReversed interacts with the draw, or when to prefer this over the multi-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 description coverage is only 40% — date, seed, and allowReversed have no schema descriptions. The description compensates with nothing beyond the word "deterministic," which only loosely gestures at the seed parameter. The date/seed semantics and the meaning of allowReversed are left entirely unexplained.

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?

"Deterministic 1-rune draw" gives a specific verb (draw) and resource (rune) with the cardinality baked in, which implicitly separates it from runes_three and runes_nine. However, it never names or contrasts those siblings explicitly, so an agent must infer the distinction from the count alone.

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 offers no when-to-use guidance, no prerequisites, and no routing to alternatives like astroway_runes_three, astroway_runes_nine, or astroway_runes_by_zodiac. The [Group] and [Cost] tags are metadata, not usage guidance.

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