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

With readOnlyHint=true and destructiveHint=false, annotations already declare safe read-only behavior. The description adds meaningful behavioral context by clarifying the response returns summary data and not full healing properties, and by directing to an alternative endpoint for richer data. No contradictions with annotations.

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?

Four focused sentences with the primary action and scope in the first sentence. The reference to the detail endpoint is placed early. The final sentence about personalized recommendations provides use-case context without tautology or fluff; no unnecessary information.

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 filtered list tool with comprehensive annotations, a complete input schema covering all params, and no output schema, this description is sufficient. It clarifies return granularity (summary vs. detail), confirms zodiac coverage, and matches exactly the portfolio it's built for. Nothing needed to call the tool correctly is missing.

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 all parameters (sign, lang, limit, offset, compact) are already well-documented with types, enums, defaults, and examples. The description contributes little beyond listing 'sign' values via 'all 12 zodiac signs,' which does not add semantic value beyond what the schema already states, so the 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?

The description uses a specific verb and resource: 'Get healing crystals and gemstones associated with a specific zodiac sign.' It covers all 12 signs, clearly distinguishing this tool from other crystal-filter siblings like chakra, planets, or colors.

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?

It states that summary data is returned for each crystal and points to '/crystals/{id}' detail endpoint when full healing properties are needed, giving clear context for when this tool's output is sufficient. It doesn't explicitly compare against other sibling filter endpoints (planets, element, etc.), but the zodiac-specific scope plus the detail-endpoint alternative gives solid guidance.

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