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

Annotations already declare this safe read-only idempotent behavior, so the description does not need to restate safety. It does add useful context by disclosing the methodology (NOAA/Meeus approximations, lunar parallax) and that results are 'model-conditional,' which signals approximation limits. It omits permission needs or accuracy bounds beyond that, so it is solid but not rich.

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 dense, front-loaded sentences with no filler: the action and target come first, the methodology and return content follow. It is appropriately sized, though the technical phrasing is slightly terse.

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 partially compensates by naming the return (angular consistency and lunar phase). However, given 7 parameters at 0% schema coverage and no output schema, it leaves significant gaps about input formats and result structure that an agent would need.

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 0% across 7 parameters, so the description carries the full burden and largely fails: it does not explain date_utc's fixed format, the tolerance_deg default/units, latitude/longitude ranges, or the azimuth/elevation claimed values. Only the Sun/Moon choice and UTC time/location are vaguely echoed from the schema.

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 (check) and resource (a claimed Sun or Moon position) and scopes the inputs (UTC time/location), which lets an agent distinguish it from siblings like verify_shadows or check_shadow_track. It stops short of naming those siblings or drawing an explicit boundary, so it is clear but not fully differentiated.

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?

No when-to-use, when-not-to-use, or alternative guidance is given. It is implied the tool verifies a claimed position, but an agent gets no routing help against check_shadow_track, verify_shadows, or triangulate_tracks, which are plausible overlapping siblings.

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