Astro Agents - verifiable planetary timing data and astrology

Catalog (free)

astro_catalog

Read-onlyIdempotent

List every astrology, ephemeris and financial-astrology (trading backtest) tool with its price, input schema and an example request: planet positions, event calendar (eclipses, Mercury retrograde), Gann planetary lines, sky analogues, natal and Vedic charts. Free; call it first to pick the right tool.

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": "astro_catalog"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description
`calls`	Yes	The $0.01-0.02 tools: MCP tool name, price, REST route, what it computes and an example request (input schemas are in tools/list).
`payment`	No	Free calls, payment protocols (x402, MPP) and networks.
`premium`	Yes	The full-chart tools, same fields as 'calls'.
`service`	Yes	Service name.
`support`	No	Contact, documentation and policies.
`tagline`	No	One-line summary of the service.
`accuracy`	No	Headline of the accuracy benchmark against NASA/JPL Horizons (largest deviations in arcseconds) with links to the details.
`discovery`	No	Discovery documents: OpenAPI, MCP server card, A2A agent card.
`whats_new`	No	What the current release added (version, date, and each new tool or proof with its route, price and summary).
`start_here`	No	Which tool to call first for common questions.
`engine_version`	No	Calculation engine version.
`free_endpoints`	No	Endpoints that are always free (catalog, verify, health, benchmark).
`why_use_this_instead_of_computing_it_yourself`	No	Reasons to prefer these tools over computing a chart yourself.

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedOct 27, 2026

addedOutput schema / properties / accuracy

Added value: +{
+  "description": "Headline of the accuracy benchmark against NASA/JPL Horizons (largest deviations in arcseconds) with links to the details.",
+  "type": "object"
+}

changedOutput schema / properties / free_endpoints / description

Previous value: -"Endpoints that are always free (catalog, verify, health)."New value: +"Endpoints that are always free (catalog, verify, health, benchmark)."

addedOutput schema / properties / whats_new

Added value: +{
+  "description": "What the current release added (version, date, and each new tool or proof with its route, price and summary).",
+  "type": "object"
+}

Changed1 schema field changedOct 6, 2026

changedOutput schema / properties / calls / description

Previous value: -"The $0.01-0.02 tools: name, price, REST route, input schema and an example request."New value: +"The $0.01-0.02 tools: MCP tool name, price, REST route, what it computes and an example request (input schemas are in tools/list)."

Changed1 schema field changedOct 6, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "calls": {
+      "description": "The $0.01-0.02 tools: name, price, REST route, input schema and an example request.",
+      "type": "array"
+    },
+    "discovery": {
+      "description": "Discovery documents: OpenAPI, MCP server card, A2A agent card.",
+      "type": "object"
+    },
+    "engine_version": {
+      "description": "Calculation engine version.",
+      "type": "string"
+    },
+    "free_endpoints": {
+      "description": "Endpoints that are always free (catalog, verify, health).",
+      "type": "object"
+    },
+    "payment": {
+      "description": "Free calls, payment protocols (x402, MPP) and networks.",
+      "type": "object"
+    },
+    "premium": {
+      "description": "The full-chart tools, same fields as 'calls'.",
+      "type": "array"
+    },
+    "service": {
+      "description": "Service name.",
+      "type": "string"
+    },
+    "start_here": {
+      "description": "Which tool to call first for common questions.",
+      "type": "string"
+    },
+    "support": {
+      "description": "Contact, documentation and policies.",
+      "type": "object"
+    },
+    "tagline": {
+      "description": "One-line summary of the service.",
+      "type": "string"
+    },
+    "why_use_this_instead_of_computing_it_yourself": {
+      "description": "Reasons to prefer these tools over computing a chart yourself.",
+      "type": "array"
+    }
+  },
+  "required": [
+    "service",
+    "calls",
+    "premium"
+  ],
+  "type": "object"
+}

First observedOct 3, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context beyond them: each catalog entry carries price, input schema and an example request, and the tool is free to call. It doesn't say whether returned schemas should be reused verbatim when invoking the listed tools, a minor gap.

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 verb and the payoff (price, schema, example request) before the domain keyword list, and the closing sentence carries the routing instruction. The enumerated subject areas read slightly like keyword stuffing, but each maps to a real sibling tool an agent might be searching for, so the length is largely earned.

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?

With an output schema present and rich annotations, the description needn't explain return values, and it still adds what the entries contain. Combined with 'call it first', an agent has everything needed to decide to invoke it; only the follow-up convention (reuse the returned schema as-is) is left implicit.

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?

Zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description correctly avoids inventing parameter-like details for a parameterless tool.

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 ('List') and resource ('every astrology, ephemeris and financial-astrology tool with its price, input schema and an example request'), which no sibling tool does. The domain list (planet positions, event calendar, Gann lines, natal/Vedic charts) makes it unmistakable against siblings like planet_positions or natal_chart.

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?

'Free; call it first to pick the right tool' gives explicit sequencing guidance relative to the 21 sibling tools, which is exactly the routing decision an agent faces. It lacks an explicit 'when not to use', but for a zero-param entry-point catalog there is no plausible competing tool, so the guidance is effectively complete.

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

All Astro Agents - verifiable planetary timing data and astrology tools Inspect

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