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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds meaningful behavioral context beyond them: no refraction/terrain/weather modeling, a warning that numerical tolerance is not astronomical accuracy, and a caveat on validation coverage and non-independence of shared solar models. This is genuinely useful limitation disclosure.

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?

The definition leads with the core computation and angle ranges, then appends limits. It is dense but every sentence carries a distinct caveat or scope. The final two sentences on oracle validation and shared-model non-independence are slightly tangential but still earn place as trust caveats.

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 an output schema present and full schema description coverage, the description need not explain returns or parameters, and it correctly focuses on conventions and model limitations. Coverage is solid; the only gap is absent guidance about when to prefer this over related sibling tools.

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 the schema already documents date_utc, latitude, and longitude in detail (including polarity, bounds, and validation rules). The description adds nothing about parameter format or constraints beyond the output angle ranges, so the baseline 3 applies.

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 and resource: computing geometric golden [-4,+6°] and blue [-6,-4°] windows for one UTC day. The scope, angle bounds, and time range are concrete, so an agent knows exactly what is produced. It does not explicitly distinguish itself from sibling solar tools like check_ephemeris or check_shadow_track, which keeps it below a 5.

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 guidance and no routing to alternatives. The clause 'Sunrise at -0.833° is a separate convention' clarifies a boundary but is a disambiguation caveat, not usage direction. An agent gets no explicit signal about when this tool is preferred over the many related solar/ephemeris siblings.

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