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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, but the description adds real value beyond them: it commits to determinism, names the output band scale (Dawn→Divine), the percentile, and a 5-of-26 consensus preview. It does not disclose error behaviour for out-of-range or future dates, which is the remaining gap.

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 sentences, front-loaded with the purpose and result scale before the supporting detail. The enumerated list of systems is slightly verbose ('and 19 others') but it earns its place by conveying scope; nothing is padded.

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 no output schema, the description steps in to describe the return payload (score, band, percentile, per-system preview), which is exactly what an agent needs. Only the failure mode for invalid dates and the lat/lon defaults' effect on results are left unaddressed.

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 every parameter including defaults (Bangkok lat/lon, noon hour) is already documented in the schema. The description adds no parameter-level meaning such as how hour precision changes the BaZi/Vedic subsystem weighting beyond what the schema states.

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?

States a specific verb (Compute) plus a named resource with an explicit range (Mythsensus Cosmic Score 1–1,000 for a birth date), and the synthesised-systems detail makes it unmistakably distinct from siblings like get_deep_reading or list_26_systems.

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?

The trigger condition (you have a birth date and want a score) is implied clearly by the description, but there is no explicit when-to-use vs when-not-to-use guidance and no named alternative such as get_deep_reading for a fuller narrative reading.

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