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 useful non-schema context: the tag dimensions present in each entry, the fact that chakra/purpose taxonomies are returned, and the 5-credit (Tier ½) cost. It stops short of describing pagination or result-size behavior for a 'full directory'.

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?

Two front-loaded sentences state the resource and its return taxonomies with no filler, followed by compact bracket metadata for group, endpoint, and cost. Slightly more could be trimmed from the tag enumeration, but nothing is wasted.

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, annotations covering safety, and a fully documented 2-parameter schema, the definition only needs to orient the agent — which it does by naming the resource, its tag fields, and what taxonomies come back. The remaining gap is the lack of explicit routing to the filtered crystal 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 100%, so both `fields` (dotted-path projection) and `precision` (decimal rounding) are fully documented in the schema, and baseline is 3. The description adds nothing about either parameter — notably it does not hint that `fields` can be used to trim this large directory response.

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 states a specific resource and scope: a 'reference list of crystals' with named tag dimensions (chakra, zodiac, planet, element, hardness, purpose), which is clearly distinguishable from the geomancy, runes, and Mayan siblings. It does not, however, name the closely related siblings (astroway_esoteric_crystals_by_chakra_chakra, _by_purpose_purpose, _by_zodiac_sign, _recommend) to explain how this differs from them.

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 line 'Returns chakra and purpose taxonomies for filtering' implies the intended pipeline: call this first to discover valid filter values, then use the filtered crystal endpoints. That is genuine but implied guidance — there is no explicit statement of when to prefer this over the by_chakra/by_purpose/by_zodiac variants, nor any exclusion.

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