Crystals by Planet

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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the description only needed to add context. It does: the endpoint path and the cost note ('see your plan — endpoint not in the public credit manifest') warn the agent that billing is uncertain, which is genuinely useful operational information not present in structured fields. Return shape is left to the output schema.

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?

One front-loaded functional sentence followed by bracketed metadata (group, endpoint, required param, cost). No wasted prose. Minor redundancy: the enum list in the description duplicates the schema enum verbatim.

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 one-parameter lookup with a full output schema and complete annotations, this is close to sufficient: resource meaning, endpoint, required parameter and cost caveat are all present. A brief pointer to the sibling filters by chakra/purpose/zodiac would make it complete.

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 100% and the single parameter carries an enum plus a 'case-insensitive' note, so the schema does the heavy lifting. The description restates the same enum values in prose but adds no new meaning such as default behavior or how invalid values are handled; baseline 3 applies.

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 resource and filter: crystals whose traditional planetary correspondence is the given planet. The parenthetical enumeration pins down the accepted values, so an agent can distinguish it from the by-chakra, by-purpose and by-zodiac siblings without opening a schema, though no sibling is named explicitly.

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?

Usage is only implied: 'given a planet, get its crystals.' There is no statement of when to prefer this over astroway_esoteric_crystals_by_chakra_chakra or astroway_esoteric_crystals, nor any exclusion or prerequisite. The '[Required: planet]' line confirms the minimal call shape but is not routing guidance.

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