Monthly Ephemeris - Daily tropical planetary positions for a month

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered; the description adds genuinely useful behavior: calculation is at noon UTC, the year/month omission yields the current month, and the data is verified against NASA JPL Horizons. It does not mention rate limits or output shape, but the output schema covers the latter.

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 core sentences are front-loaded and information-dense, but the closing 'Monthly ephemeris API, tropical position table, daily planet transit positions, ecliptic longitude calculator' is keyword stuffing that restates the same concept four ways and dilutes the definition.

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, the description need not explain return values, and it does cover the bodies, the time basis, and the default-date behavior. All parameters are optional and their defaults are documented, so an agent has enough to call it correctly; only the lang and compact options go unmentioned in prose.

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 baseline is 3; the schema already documents ranges, defaults, and the lang enum. The description adds only the motivation for the year/month default ('so a published ephemeris page stays current without a redeploy') and says nothing about lang or compact, so it does not meaningfully exceed 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 and resource ('Get daily tropical ecliptic positions for all 14 Western bodies ... for an entire month') and enumerates exactly which bodies are covered, so scope is unambiguous. It differentiates itself from single-day siblings through the explicit monthly scope, though it never names the closest alternatives (e.g. post_astrology_planets, post_astrology_transits_monthly) to sharpen the distinction.

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?

Offers use cases ('ephemeris tables, transit tracking, retrograde calendars, planetary movement charts') and one concrete operational hint ('Omit year and month to get the month in progress'), which implies when the tool fits. However, it gives no guidance on when to prefer this over the daily/single-planet or transit-monthly siblings, and no exclusions.

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