astroway-mcp

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by astroway

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TypeScript

Remote

Davison Chart

astroway_relational_davison

Read-onlyIdempotent

Calculates a Davison relationship chart from the midpoint in time and space between two birth moments, so you can compare two people's charts.

Instructions

Calculate a Davison relationship chart using the midpoint in time and space between two birth moments.

[Group: Comparisons] [Endpoint: POST /v1/davison] [Required: chart1, chart2] [Cost: 50 credits (Tier 3)]

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "chart1": "<chart1>",
      "chart2": "<chart2>"
    },
    "name": "astroway_relational_davison"
  }
}

Input Schema

Name	Required	Description	Default
`chart1`	Yes	Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single house-system letter, P by default; a name such as "Placidus" is refused, and the case matters because I and i are two different Sunshine systems.
`chart2`	Yes	Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single house-system letter, P by default; a name such as "Placidus" is refused, and the case matters because I and i are two different Sunshine systems.

Output Schema

Name	Required	Description	Default
`meta`	No
`input`	No
`houses`	No
`aspects`	No
`planets`	No
`antiscia`	No
`midpoint`	No
`chartSect`	No
`julianDay`	No
`houseAspects`	No
`siderealTime`	No
`antisciaAspects`	No
`parallelAspects`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv1.6.1Nov 9, 2026

changedInput schema / properties / chart1 / description

Previous value: -"Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single Swiss Ephemeris letter, P by default; a name such as \"Placidus\" is refused, and the case matters because I and i are two different Sunshine systems."New value: +"Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single house-system letter, P by default; a name such as \"Placidus\" is refused, and the case matters because I and i are two different Sunshine systems."

changedInput schema / properties / chart2 / description

Previous value: -"Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single Swiss Ephemeris letter, P by default; a name such as \"Placidus\" is refused, and the case matters because I and i are two different Sunshine systems."New value: +"Birth data for a single natal chart. Required: date (YYYY-MM-DD), time (HH:mm:ss), latitude and longitude in decimal degrees. The short forms lat, lon, lng and tz are rejected with 400 INVALID_FIELD; pass the full names. timezoneOffset is hours from UTC and defaults to 0, meaning UTC; send timezone instead (an IANA name such as Europe/Kyiv, or auto) and the offset for that date is worked out, summer time included. city is a display label only: nothing here geocodes it, so it never stands in for coordinates. houseSystem is a single house-system letter, P by default; a name such as \"Placidus\" is refused, and the case matters because I and i are two different Sunshine systems."

Addedv1.6.0Oct 24, 2026

TDQS

B3.2/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds genuinely useful context beyond them: the endpoint (POST /v1/davison) and a billing cost of 50 credits at Tier 3, which an agent needs for cost-aware planning. It says nothing about latency, rate limits, or what the returned chart contains, though the presence of an output schema reduces the need for 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.

Conciseness4/5

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

One front-loaded sentence states the operation and its defining method, followed by compact bracketed metadata lines for group, endpoint, required params and cost. The required-params line duplicates the schema's required array and is the only real redundancy. Nothing else is wasted.

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

Completeness3/5

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

For correct invocation the definition is adequate: purpose, required inputs, endpoint and cost are all present, and the output schema plus annotations cover return values and safety. The gap is selection context — with roughly a dozen relational siblings, an agent has no basis in this description for choosing Davison over composite or synastry.

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%, and the nested chart1/chart2 objects carry detailed field-level documentation (timezone vs timezoneOffset, houseSystem letters, ayanamsa schools, rejected short forms). The description only restates '[Required: chart1, chart2]', which the schema's required array already declares. Baseline 3 applies because the schema does all the semantic heavy lifting.

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

Purpose4/5

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

The description names a specific verb and resource ('Calculate a Davison relationship chart') and adds the defining mechanism, 'midpoint in time and space between two birth moments,' which is exactly what separates a Davison chart from a composite. It never names the sibling it differs from, but the method description is precise enough that an agent can identify the operation without opening the schema.

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

Usage Guidelines2/5

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

There is no when-to-use guidance beyond the '[Group: Comparisons]' tag. The definition never says when an agent should pick a Davison chart over astroway_relational_composite, astroway_relational_synastry, or astroway_relational_coalescent, which is the key decision an agent faces given the dense relational-tool family. It also gives no prerequisites or exclusions.

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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