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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds genuine extra context — that results carry type, date, and geographic visibility data, and that the call costs 100 credits (Tier 4) — but says nothing about result volume, pagination, or whether the year/range inputs interact.

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?

Two tight sentences with the capability stated first and the return contents second; the bracketed group/cost metadata is compact and skimmable. No filler, though the cost/group lines are boilerplate rather than description prose.

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-shape explanation is not strictly required, and the description does gesture at it. However, for a tool with a required-but-nullable year, an undocumented range cap, and two nearby eclipse siblings, the description leaves the agent short of what it needs to choose and call confidently.

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 50%: 'fields' and 'precision' are documented in the schema, while 'year' (nullable but required) and 'yearsRange' (max 20) are not. The description's 'year or multi-year range' hint loosely maps to those two params, but does not explain the required-but-nullable year, the 20-year cap, or how the two interact — so it only partly compensates for the gap.

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 ('Find') plus a precise resource ('solar and lunar eclipses') and scope ('within a given year or multi-year range'). It clearly distinguishes itself from generic calendar tools, but never acknowledges the close siblings astroway_geo_eclipse_analysis or astroway_render_eclipse_path, which an agent would reasonably confuse with this one.

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 phrase 'within a given year or multi-year range' implies when the tool applies, but there is no explicit when-to-use guidance, no exclusion of overlapping siblings, and no statement of prerequisites. Usage must be inferred from the purpose sentence alone.

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