AstroWay Chinese metaphysics

Hidden stems (Cang Gan)

astroway_bazi_hidden_stems

Read-onlyIdempotent

The one to three stems each branch shelters, with role and weight. This is where most of a chart's elements live: a chart with no visible Water can still be soaked in it. On the four storage branches the middle role belongs to the stored element, not to the second in the list.

[Group: BaZi (Four Pillars)] [Endpoint: POST /v1/bazi/hidden-stems] [Required: date] [Cost: 10 credits (Tier 1)]

Input Schema

Name	Required	Description
`date`	Yes
`time`	No
`fields`	No	Compact mode: comma-separated dotted paths to keep, relative to `data`, e.g. "planets.name,planets.longitude,houses.cusp". Omit for the whole response.
`gender`	No
`language`	No
`timezone`	No	IANA zone name such as Europe/Kyiv, or auto to look the zone up from latitude and longitude. The server takes the offset that zone kept at this local date and time, summer time included, and uses it in place of timezoneOffset. A clock time that happened twice takes the first occurrence; one skipped when clocks went forward takes the offset from before the change. Abbreviations such as EST are refused. Before 1970 the tz database is not reliable for every place, so send timezoneOffset when the local clock is known.
`longitude`	No
`precision`	No	Compact mode: round fractional numbers to this many decimals. Longitudes carry 14 by default; 2 is finer than any chart is drawn.
`dayBoundary`	No
`includeLuck`	No
`stageSchool`	No
`trueSolarTime`	No
`timezoneOffset`	No	Ignored when timezone is sent.
`includeFullTable`	No

Output Schema

Name	Required	Description	Default
`notes`	No
`source`	No
`pillars`	No
`solarYear`	No
`weighting`	No
`disclaimer`	No
`methodology`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedOct 13, 2026

addedInput schema / properties / dayBoundary

Added value: +{
+  "enum": [
+    "23:00",
+    "midnight"
+  ],
+  "type": "string"
+}

addedInput schema / properties / gender

Added value: +{
+  "enum": [
+    "male",
+    "female"
+  ],
+  "type": "string"
+}

addedInput schema / properties / includeLuck
```
Added value: +{
+  "type": "boolean"
+}
```

First observedOct 5, 2026

TDQS

B3.4/5.0

Behavior4/5

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

Annotations already declare read-only, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds real behavioral context beyond that: it discloses the storage-branch quirk where the middle role belongs to the stored element rather than the second list entry, which warns the agent about a non-obvious output layout. It stops short of describing permissions, cost, or caching, but the metadata block supplies the cost.

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?

Three front-loaded sentences, each carrying content: what is returned, why it matters, and one edge-case caveat. The vivid 'soaked in Water' line earns its place by motivating use. The structured metadata footer is compact and does not pad the text.

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?

Return values need not be explained because an output schema exists, and the output semantics are described well. However, for a 14-parameter computation tool, the description gives no guidance on which optional BaZi switches to set or what the required input is beyond the footer, leaving the input side thin.

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 only 29% across 14 parameters, and the prose mentions no parameter at all — the reader learns only from the metadata footer that `date` is required. Domain-specific inputs such as dayBoundary, stageSchool, trueSolarTime, and includeFullTable are left entirely to the sparse schema, so the description fails to compensate for the coverage gap.

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?

Names a specific resource — the one-to-three hidden stems sheltered in each BaZi branch, with role and weight — and the description makes clear this is the elementally meaningful layer of the chart. It is more specific than the title alone, but it never distinguishes itself from the many BaZi siblings (bazi_chart, bazi_four_pillars, bazi_element_balance), so an agent must infer which computes the same layer.

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

Usage Guidelines3/5

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

The remark that 'this is where most of a chart's elements live' implies the tool is the right one when hidden element counts matter, but no explicit when-to-use, when-not, or alternative tool is named. With ~20 BaZi siblings, routing guidance is the missing piece.

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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