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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds non-obvious behavioral facts beyond that: no weighting is applied, each factor carries frame provenance (Moon/Lagna/natal/none), a verdict-or-null, rule source and signification ids, and whether it depends on birth time. It also states the day's sky is sampled at local noon, which materially affects interpretation of results.

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?

Front-loaded purpose sentence, then labeled WORKFLOW / INPUT CONTRACT / DO NOT CONFUSE WITH blocks, then a docs link. Efficient and skimmable; the factor-attribute sentence is dense list-like prose, slightly telegraphic, but each clause adds distinct 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?

An output schema exists so return values needn't be restated, and the description still summarizes payload shape; parameter defaults, required birth object, routing to prerequisite and follow-on tools, and a full contract URL are all present. Nothing an agent needs to call this 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 coverage is 100% so the baseline is 3, but the description adds defaults and interaction semantics the schema only states in isolation: target_date defaults to today in the birth timezone, target_timezone defaults to the birth timezone, and the noon sampling rule. Only response_format is left untouched by the prose.

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+resource with precise scope: 'every classical factor for one person on one day, in one shape, with no weighting.' The 'DO NOT CONFUSE WITH' block explicitly separates it from asterwise_get_gochar (transit section only) and asterwise_get_horoscope (AI-written text), which is exactly what sibling differentiation requires.

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?

WORKFLOW gives both orderings (BEFORE: get_natal_chart; AFTER: get_vedic_events for the ranged timeline), and the exclusion list names the two closest alternatives with the condition that selects them. An agent can route without inference.

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