Cazimi: retrograde planets

Planet positions at a moment

planet_positions

Read-onlyIdempotent

Geocentric tropical longitude, sign and degree, ecliptic latitude, daily speed and retrograde flag of the Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto and the mean North Node at a moment, 1900–2100. Computed live from the ephemeris (astronomy-engine, about 1′), tropical zodiac on the true ecliptic of date, geocentric, UTC. Astronomical positions only, no interpretation. Paid tool: $0.005 per call in USDC on Base via x402 (HTTP 402 with payment requirements; retry with a PAYMENT-SIGNATURE header). Free tools cover the current status and the next retrograde.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "planet_positions"
  }
}

Input Schema

Name	Required	Description	Default
`datetime`	No	Moment as ISO UTC timestamp or YYYY-MM-DD (12:00 UTC). Defaults to now.

Schema Changelog

Changes observed during successful MCP inspections.

AddedNov 7, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations only cover safety profile (readOnly, idempotent, non-destructive); the description adds the substantive behavior an agent actually needs: live ephemeris computation, ~1′ accuracy, tropical/true-ecliptic/geocentric convention, UTC, valid range 1900–2100. It also discloses the payment flow in full (x402, HTTP 402 response, retry with PAYMENT-SIGNATURE header, $0.005/call), which is critical pre-invocation context.

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?

The output fields are front-loaded in one dense clause, followed by conventions, scope limits, and payment terms in a logical progression. No filler sentences, though the opening sentence is long enough to require careful parsing.

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

Completeness5/5

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

With no output schema, the description carries the burden of describing the return payload and does so explicitly (longitude, sign, degree, latitude, speed, retrograde flag per body). Combined with the date range, precision, and payment mechanics, an agent has everything needed to call and interpret it.

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

Parameters4/5

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

Schema coverage is 100% and the parameter already documents the ISO/date-only format and the 12:00 UTC and now defaults. The description still adds the valid date window (1900–2100) and reinforces UTC interpretation, which the schema omits.

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?

The description gives a precise resource (geocentric tropical positions of 13 named bodies) plus exact coordinate conventions: tropical longitude, sign and degree, ecliptic latitude, daily speed, retrograde flag. It is clearly distinguishable from siblings like natal_chart (interpretive) and the various retrograde-only tools.

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

Usage Guidelines4/5

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

It states the domain boundary explicitly ('Astronomical positions only, no interpretation') and routes the agent away from paid calls toward free tools for current status and the next retrograde. It does not name which sibling covers which case (e.g. is_mercury_retrograde vs. moon_now), so the alternative routing stays somewhat generic.

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

All Cazimi: retrograde planets tools Inspect

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