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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description's genuine addition is the 10-credit cost tier, which is useful behavioral context, but it says nothing about what content is returned or whether any prerequisites apply.

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?

Very short and front-loaded, and the group/cost tags are cleanly bracketed. However, the three flavor sentences consume the entire description without helping an agent select or invoke the tool, so they do not earn their place.

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?

An output schema exists, so return values need not be explained, and the tool takes no required parameters. Still, for a content-retrieval tool the description never states that it returns a deep interpretive profile for Virgo, leaving the agent to reconstruct that from the name and sibling set.

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?

Both parameters ('fields', 'precision') are documented at 100% schema coverage with examples and defaults, so the schema carries the full burden. The description adds no parameter meaning beyond that, making the baseline 3 appropriate.

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 body ('Discerning service, refined craft. Ruler Mercury. I ANALYZE.') is thematic flavor about Virgo, not a statement of what the tool does or returns. The only structural signal is the '[Group: Zodiac Signs (Per-Sign Deep)]' tag, which categorizes but does not describe an action; the actual purpose must be inferred from the tool name and title.

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?

No when-to-use, when-not-to-use, or alternative guidance is given. The '[Cost: 10 credits (Tier 1)]' tag is the only selection-relevant fact, and it says nothing about when this per-sign deep tool should be chosen over its eleven per-sign siblings.

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