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astroway-mcp

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Natal Chart

chart
Read-onlyIdempotent

Calculate a full natal chart with planets, house cusps, aspects, and angular data from birth date, time, and location.

Instructions

Calculate a full natal chart: planets, house cusps, aspects, sect, and angular data for a given birth moment.

[Group: Core] [Cost: 20 credits (Tier 2)]

Example request body: {"date":"1990-05-15","time":"14:30:00","timezoneOffset":3,"latitude":50.45,"longitude":30.52}

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
dateYes
timeYes
timezoneOffsetNo
latitudeNo
longitudeNo
houseSystemNoP
nameNo
cityNo
zodiacTypeNo
ayanamsaIdNo
cosmogramNo
Behavior3/5

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, so the tool is safe and idempotent. The description adds that it calculates specific data (planets, houses, etc.) and includes cost info, but no further behavioral traits like rate limits or error handling. With good annotations, a 3 is appropriate.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

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

The description is concise: two sentences plus a group/cost tag and example. It is well-structured with the main action first, then output components, then metadata. No unnecessary words, and the example is helpful.

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

Completeness2/5

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

The tool has 11 parameters and no output schema. The description lists output components but does not describe the return format or structure. Many optional parameters (e.g., zodiacType, ayanamsaId) are left unexplained. Given the complexity, the description is incomplete for full agent understanding.

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

Parameters2/5

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

Schema description coverage is 0%, meaning the input schema lacks parameter descriptions. The description only provides an example request body, which shows usage for some parameters but does not explain others like houseSystem, zodiacType, ayanamsaId, or cosmogram. This forces the agent to infer meaning from parameter names alone, which is insufficient.

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 clearly states 'Calculate a full natal chart: planets, house cusps, aspects, sect, and angular data for a given birth moment'. The verb 'Calculate' is specific and the resource 'natal chart' is distinct from sibling tools like 'composite' or 'synastry', making the purpose unambiguous.

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?

The title 'Natal Chart' and group tag '[Group: Core]' strongly imply this is the primary tool for complete birth charts. However, the description does not explicitly guide when to use this tool over alternatives like 'planets', 'houses', or 'aspects', nor does it mention when not to use it. The example request partially compensates.

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

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