VGC Teambuilder

Calculate damage for one move

calculate_damage

Read-onlyIdempotent

Calculate how much damage one move does from one Pokémon to another in Pokémon Champions doubles: the damage range, the share of the defender's HP, and the chance to knock it out. Use it instead of estimating damage. Any part of a set that is left out is filled in from the regulation's usage statistics and listed under assumptions. A move that hits both opponents is calculated at its reduced doubles damage unless singleTarget is set. This is one calculation, not a battle simulation: it does not account for the rest of the turn, switching or luck beyond the damage roll and critical hits.

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": {
      "attacker": "<attacker>",
      "defender": "<defender>",
      "move": "<move>"
    },
    "name": "calculate_damage"
  }
}

Input Schema

Name	Required	Description
`move`	Yes	Move name, for example "Earthquake"
`field`	No	Battle conditions. Leave out for none.
`format`	No	Regulation id from list_formats. Defaults to "champions-regmc" (Pokémon Champions — Regulation M-C).
`attacker`	Yes	The Pokémon using the move
`defender`	Yes	The Pokémon being hit

Output Schema

Name	Required	Description
`move`	Yes
`damage`	Yes
`format`	Yes	Regulation id the result applies to
`attacker`	Yes
`defender`	Yes
`knockOut`	No	Absent when the move deals no damage
`conditions`	Yes
`formatName`	Yes	Display name of the regulation
`assumptions`	Yes	Everything the calculation assumed, including any part of a set that was filled in because it was not given. Tell the user about these.
`description`	Yes	The calculation in standard damage-calc notation
`noDamageReason`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 13, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations already declare this a read-only, idempotent, closed-world computation, so the bar is lower, yet the description still adds substantive behavior: omitted set details are filled from regulation usage statistics and surfaced under `assumptions`, and spread moves are reduced per doubles rules unless `singleTarget` is set. These are non-obvious defaults an agent could not infer from annotations or the schema alone.

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?

Four sentences with no filler. Purpose and outputs come first, then the estimation alternative, then the defaulting behavior, then the scope limits — a well front-loaded order.

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

Completeness5/5

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

For a nested five-parameter calculation tool with an output schema, this covers what an agent needs: what it computes, how missing inputs are resolved, the doubles spread-move rule, and where its modeling stops. Return values are left to the output schema, as appropriate.

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?

Schema coverage is 100%, so baseline is 3, but the description adds meaning the schema lacks: which omissions trigger usage-statistic defaulting and that those defaults appear in an `assumptions` output, plus the spread-move/singleTarget interaction. It does not elaborate on the `field` conditions, but the schema already documents those.

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?

"Calculate how much damage one move does from one Pokémon to another" gives a specific verb and resource, and it names the exact outputs (damage range, share of defender's HP, KO chance). No sibling in the list performs damage calculation, so the scope is 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?

"Use it instead of estimating damage" gives a clear trigger, and the closing sentence sets explicit boundaries (one calculation, not a battle simulation; no switching, other turn actions, or luck outside damage rolls and crits). It does not route to a named alternative tool, but the guidance on when and when-not is otherwise concrete.

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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