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 genuine context (10 credits, Tier 1, group name), but it does not clarify whether the result is a fixed reference listing or a randomized draw, which is the key behavioral question for a rune tool.

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?

"All 24 runes." is front-loaded and the rest is compact metadata (group, cost/tier) that earns its place as operational context. Nothing is wasted, though the tag formatting is boilerplate rather than explanatory prose.

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-value shape needn't be described, and both parameters are schema-documented. The remaining gap is guidance on how this relates to the other rune tools and whether the list is static, which the description leaves unaddressed.

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 100% and both parameters (fields, precision) are fully documented in the schema, including the compact-mode syntax and precision bounds. The description adds nothing about parameters, so baseline 3 is correct.

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?

"All 24 runes" names the resource and its completeness (the full Elder Futhark set of 24), which implicitly separates it from siblings like astroway_runes_single, astroway_runes_three, or astroway_runes_nine that return subsets. The verb is only implied, but an agent can tell what this returns without opening the schema.

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 statement of when to pick this over astroway_runes_single/three/nine/by_zodiac, nor any prerequisite or exclusion. The agent must infer from the sibling names alone that this is the catalog/reference call.

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