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CycleCalcs Astronomy

by com.cyclecalcs
OverviewDiscussionsAdmin

All planets at a glance

astro_planet_board
Read-onlyIdempotent

All eight planets in one call for a date and optional location: constellation, magnitude, apparent size, elongation from the Sun, morning or evening sky, retrograde state with the next station, rise/set, and a worth-looking-tonight assessment. The right tool for "which planets are visible tonight". For exact coordinates of specific bodies use astro_positions.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
tzNoIANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone.
latNoLatitude in decimal degrees, north positive. Send lat and lon together.
lonNoLongitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together.
dateNoISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Or jd: followed by a Julian Day on the UT scale, e.g. "jd:2461000.5". On astro_positions, date may list up to 24 datetimes separated by commas, answered in the order sent. Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the ephemeris is not reliable there.
sortNoOptional result ordering. Default is by distance from the Sun.
placeNoPlace name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attribution field, which must be preserved when shown.
bodiesNoOptional subset of planets: mercury, venus, mars, jupiter, saturn, uranus, neptune, pluto.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
dataYesWhich planets are worth looking at right now, and where.
rightsNoEither unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown.
warningsNoMachine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded.
attributionNoThe credit line to display verbatim when rights is attribution_required.
next_cursorNoPresent only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page.
not_computedNoData this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists".

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • changedInput schema / properties / date / description
      Previous value: -"ISO 8601 UTC date or datetime, e.g. \"2026-08-06\" or \"2026-08-06T21:00:00Z\". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the ephemeris is not reliable there."New value: +"ISO 8601 UTC date or datetime, e.g. \"2026-08-06\" or \"2026-08-06T21:00:00Z\". Or jd: followed by a Julian Day on the UT scale, e.g. \"jd:2461000.5\". On astro_positions, date may list up to 24 datetimes separated by commas, answered in the order sent. Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the ephemeris is not reliable there."
  2. Changed1 schema field changed
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "description": "The MCP projection of a CycleCalcs v2 response: the answer, plus the provenance a caller needs to use it honestly.",
+  "properties": {
+    "attribution": {
+      "description": "The credit line to display verbatim when rights is attribution_required.",
+      "type": "string"
+    },
+    "data": {
+      "additionalProperties": true,
+      "description": "Which planets are worth looking at right now, and where.",
+      "properties": {
+        "above_horizon_now": {
+          "description": "Bodies above the horizon, visible or not.",
+          "type": "array"
+        },
+        "bodies": {
+          "description": "Every body with position, brightness and a visibility verdict.",
+          "type": "array"
+        },
+        "count": {
+          "description": "How many bodies are on the board.",
+          "type": "integer"
+        },
+        "instant": {
+          "description": "The moment evaluated.",
+          "type": "string"
+        },
+        "observable_now": {
+          "description": "Bodies both up and realistically visible.",
+          "type": "array"
+        },
+        "retrograde_now": {
+          "description": "Bodies currently in apparent retrograde motion.",
+          "type": "array"
+        },
+        "summary": {
+          "description": "A one-line reading of tonight's planets.",
+          "type": "string"
+        }
+      },
+      "type": "object"
+    },
+    "next_cursor": {
+      "description": "Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page.",
+      "type": "string"
+    },
+    "not_computed": {
+      "description": "Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as \"withheld\", never as \"none exists\".",
+      "type": "array"
+    },
+    "rights": {
+      "description": "Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown.",
+      "type": "string"
+    },
+    "warnings": {
+      "description": "Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded.",
+      "type": "array"
+    }
+  },
+  "required": [
+    "data"
+  ],
+  "type": "object"
+}
  3. First observed

TDQS

A4.1/5.0
Behavior3/5

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds useful scope context (a single call returns all eight planets, not a subset) and hints at a computed judgment field, but says nothing about auth, rate limits, or what happens when optional location is omitted. With annotations doing the heavy lifting, this is adequate 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.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core output list, then the use case, then the sibling routing — a sensible priority order with no filler. The middle enumeration of seven returned fields is long but each item is doing real discrimination work, so it is dense rather than wasteful.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return-value structure need not be explained, and rich annotations cover the safety profile while a 100%-covered schema covers parameters. The description supplies the remaining piece — sibling routing and the intended question — leaving little an agent would need beyond it. Minor gap: no note on behavior when place cannot be resolved.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so every parameter (tz, lat, lon, date, sort, place, bodies) is already documented with format, ranges and pairing rules. The description only alludes to "a date and optional location" and adds no syntax, default, or constraint detail beyond the schema. Baseline 3 applies when the schema carries the parameter burden.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb-resource pair (all eight planets in one call) and enumerates exactly what each entry carries: constellation, magnitude, apparent size, elongation, morning/evening sky, retrograde state with next station, rise/set, and a worth-looking-tonight assessment. It also explicitly distinguishes itself from astro_positions, which covers exact coordinates of specific bodies.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit use case ("which planets are visible tonight") and names the alternative tool plus the condition that selects it ("For exact coordinates of specific bodies use astro_positions"). Both the when and the when-not are stated, so no inference is required.

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

All CycleCalcs Astronomy toolsInspect
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