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 covered. The description adds genuinely useful behavioral context beyond annotations: the cost (100 credits, Tier 4) and the group membership. It does not mention auth requirements or any rate/consumption caveats.

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?

A single front-loaded sentence states the core purpose, followed by structured group/cost tags. Nothing is padded. Slightly more could have been done with the available space given the tool's parameter surface, but there is no waste.

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. For a read-only, annotated tool the safety profile is covered, but with 6 parameters at 33% schema coverage and no usage routing, the definition leaves the agent to infer too much about argument selection.

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 only 33% (6 params, only fields and precision documented). The description adds no parameter meaning at all, so it fails to compensate for the undocumented date, sign, language, and disclaimer_inline parameters. It neither clarifies defaults nor explains the compact-mode interaction.

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?

Specific verb (Generate) plus resource (year-ahead horoscope) with an explicit scope qualifier, the 12-month window, which inherently separates it from the daily/weekly/monthly siblings. It also enumerates content (transit cycles, solar return context, profection). It stops short of naming a sibling, but the scope is unambiguous.

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 when-to-use guidance and no mention of alternatives. An agent choosing between astroway_horoscope_yearly, _monthly, _weekly, and _daily gets no routing rule; the 12-month window is inferable from the name but the description does not state a selection condition.

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