DXRating

Calculate chart rating

calculate_rating

Read-onlyIdempotent

The rating a maimai DX chart gives for an achievement, the achievement a rating needs, and the rating of each rank (S to SSS+). Give a chart (looked up with its current internal level) or an internal level. Achievements are integers in 1/10000 of a percent: 100.7543% is 1007543.

Input Schema

Name	Required	Description
`song`	No	The chart: a sheet ID (dsht_…), or a song ID or name with type and difficulty. Or give internal_level.
`type`	No	Type of the chart of song: dx or std
`combo`	No	Combo lamp: fc, fcp (FC+), ap or app (AP+). AP and AP+ add 1 to the rating.
`server`	No	Game server (jp, intl, usa, cn), whose internal level is used where it differs. Default jp.
`difficulty`	No	Difficulty of the chart of song: basic … remaster
`achievement`	No	Achievement in 1/10000 of a percent, an integer: 100.7543% is 1007543, 99.5% is 995000
`target_rating`	No	A rating of the chart to reach: the lowest achievement that gives it
`internal_level`	No	Internal level (譜面定数) instead of a chart: 13.7

Output Schema

Name	Required	Description
`chart`	Yes	The chart, when one was given
`result`	Yes	The rating of achievement, when one was given
`server`	Yes
`source`	Yes
`target`	Yes
`dataAsOf`	Yes	When the catalog was last updated
`thresholds`	Yes	The rating at the lowest achievement of each rank from S to SSS+
`internalLevel`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedNov 3, 2026

removedOutput schema / properties / source / properties / license

Removed value: -{
-  "const": "CC BY-NC 4.0",
-  "type": "string"
-}

removedOutput schema / properties / source / properties / licenseUrl
```
Removed value: -{
-  "type": "string"
-}
```

changedOutput schema / properties / source / required

Previous value: -[
-  "name",
-  "url",
-  "license",
-  "licenseUrl",
-  "attribution"
-]New value: +[
+  "name",
+  "url",
+  "attribution"
+]

First observedOct 29, 2026

TDQS

B3.3/5.0

Behavior3/5

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

Annotations already declare readOnly, idempotent and non-destructive, so safety needs no restating. The description adds a genuine behavioral detail — that chart lookup uses the chart's *current* internal level, which varies by server — but the achievement unit encoding it also explains is already spelled out in the schema.

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

Conciseness3/5

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

Three sentences with no filler, but the lead sentence is a dense enumeration without a main verb, which slows parsing. The unit-conversion example partly duplicates the achievement field description.

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?

With 8 all-optional parameters and a rich output schema, the description should clarify which parameter combinations are valid (song+type+difficulty vs internal_level; achievement vs target_rating). It gestures at the first split but not the second, leaving ambiguity about a zero-required-argument call.

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%, so every parameter including server, combo and internal_level is already documented. The description only reinforces the song-vs-internal_level choice and the achievement encoding, adding little beyond the schema and nothing about how song/type/difficulty combine.

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 the three computations (rating from achievement, achievement needed for a target rating, rating of each rank S–SSS+), which is specific enough to separate it from calculate_best50 and the lookup tools. The opening sentence is a verbless list of noun phrases, so the reader has to infer 'calculate' from the tool name, and no sibling is named explicitly.

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?

"Give a chart ... or an internal level" implies the two input modes but never states when to use this tool over calculate_best50 or get_sheet. It also does not say that achievement and target_rating are alternative purposes rather than combinable inputs, leaving the agent to infer routing.

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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