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

Beyond the readOnly/idempotent/non-destructive annotations, the description discloses the 10-year range cap, inclusive UTC dates, the 3° orb and conjunction/opposition rule used for natal contacts, and the effect of house_system on Ascendant/MC computation. These are concrete behavioral traits not present in the annotations or schema.

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 core sentence followed by labeled WORKFLOW, INPUT CONTRACT and DO NOT CONFUSE WITH blocks. Every line carries actionable information; only the trailing docs URL is non-substantive but it is a pointer to a fuller contract.

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?

Result fields, range limits, optional birth semantics, and sibling disambiguation are all covered, so an agent can call this correctly without opening the output schema or the external docs. Nothing material is left to inference.

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 constraints not encoded in the schema — notably that from_date/to_date must be at most 10 years apart and are inclusive UTC — and clarifies that birth adds natal_contacts and that house_system drives Ascendant/MC.

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 states a specific resource (solar and lunar eclipses) with a scope (date range, past or future, up to 10 years) and enumerates the returned fields (type, time of greatest eclipse, start/end, eclipse degree, natal contacts). It explicitly differentiates itself from the nearest siblings moon_phase and moon_calendar.

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 is stated as BEFORE/AFTER with a named follow-up tool, and a DO NOT CONFUSE WITH block names two sibling tools and explains how they differ. The optional birth-data path is framed as a conditional add-on, so an agent knows exactly when to include it.

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