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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds meaningful context that outputs are 'uncalibrated' and 'auditable' with 'learnable factor weights', warning the agent not to treat results as finalized predictions — useful but thin beyond that one signal.

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 sentence is structurally efficient and front-loaded, but it is dense with undefined terms ('natal promise as a hard gate', 'learnable factor weights') whose meaning is not recoverable from the text itself.

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?

For an 11-parameter fusion tool with low schema coverage, the description is far too thin: it omits coordinate/timezone input rules, the date-range semantics, and what 'fusing' actually returns. The presence of an output schema excuses return-value detail, but not the missing input and routing context.

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 27% across 11 parameters, so the description bears a heavy compensation burden — yet it says nothing about any parameter (date/time, topic enum, place vs lat/long/timezone either-or, startIso/endIso range). The one required-vs-optional distinction it could clarify is left to the schema's anyOf.

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 gestures at a specific capability ('applies natal promise as a hard gate', 'returns timing windows') but is framed in architecture jargon rather than a concrete verb+resource. An agent cannot easily tell from this text how it differs from siblings like find_marriage_windows, get_timing_context, or analyze_transit_activation.

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, when-not-to-use, or alternative routing guidance. Given the many timing-adjacent siblings (find_muhurta_with_natal_fit, build_slow_transit_calendar, get_timing_context), the absence of any selection criteria 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.