Synastry Attraction Score

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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description does add genuinely useful metadata beyond annotations - the POST endpoint, required inputs, and 50-credit Tier 3 cost - but says nothing about rate limits, failure modes (e.g. missing birth time), or how the weighting is exposed in the response.

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?

The substantive sentence is front-loaded and dense with the factors that define the score; the bracketed metadata block is compact and skimmable. Nothing is redundant, though the enumeration of aspect names is long for a single sentence.

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, return values need no explanation, and parameters are fully specified in the schema. What is missing is interpretive context - what a high or low score means, whether the score is normalized by the number of contacts present, and any prerequisites on birth-time accuracy - which matters for a scored comparative tool.

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% and the nested chart object is documented in exhaustive detail (timezone handling, lat/lon naming, houseSystem letters), so the schema carries the burden. The description only restates the required pair (chart1, chart2) and adds no semantics about their ordering or role in the synastry computation.

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 names a specific output (weighted 0–100 attraction score) and enumerates the exact synastry factors it weights (Sun-Moon, Mars-Venus, ASC/DSC, 5th-house overlay), which is concrete and non-tautological. It doesn't explicitly distinguish itself from close siblings such as astroway_relational_match_score or astroway_horoscope_compatibility, so an agent must infer the difference from the name alone.

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: the endpoint, required chart1/chart2, and TIER-3 cost suggest this is the paid relationship-scoring call, but there is no explicit when-to-use or when-to-prefer-a-sibling statement. Given nearby alternatives (relational_match_score, horoscope_compatibility, relational_synastry), the absence of routing guidance is a real gap.

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