Brotato Coach

A deterministic theorycrafter for Brotato, delivered as an MCP server you can chat with from Claude Code (and other MCP clients).

The design principle: a deterministic core holds the ground truth — weapon/item/character data, DPS formulas, stat mechanics — so the language model looks facts up and computes instead of recalling (and misremembering) them. Every tool returns a finished, verifiable answer or a structured error; there are no baked-in tier lists or opinions, only facts and math.

The dataset (data/brotato.json) is not committed — it is derived from copyrighted game files, so you build it yourself from a local Brotato install (see Building the dataset). A full build from Brotato 1.1.15.4 contains 202 weapons, 197 items, 50 characters, and 15 weapon-class sets.

Requirements

• Python 3.11+

• uv for environment/dependency management

Install dependencies:

uv sync

Related MCP server: Pokemon Showdown MCP Server

Quick start

Build the dataset (needs a local extraction — see Building the dataset), then start the server:

uv run python build_dataset.py                        # writes data/brotato.json
uv run python -m brotato_coach.server                 # starts the MCP server over stdio

The server refuses to start without data/brotato.json and tells you to build it first.

Run the tests (the dataset-dependent integration test is skipped when no dataset is built):

uv run pytest        # 89 tests (88 passed + 1 skipped without a built dataset)

Run

uvx spudcoach --data /path/to/brotato.json

The dataset is never distributed — build your own from your Brotato install: uv run python build_dataset.py (see docs/extraction-setup.md). Game version auto-detects from the decompiled recovered/singletons/progress_data.gd, and generated_at defaults to the current UTC time — pass --game-version/--generated-at explicitly to override either. SPUDCOACH_DATA works as an env-var alternative to --data.

Use as a Claude Code plugin

The MCP server is described by plugin/.mcp.json:

{
  "mcpServers": {
    "spudcoach": {
      "command": "uv",
      "args": ["run", "python", "-m", "brotato_coach.server"],
      "cwd": "${CLAUDE_PLUGIN_ROOT}"
    }
  }
}

The server reads the (locally built) data/brotato.json relative to its working directory, so it must run with the repository root as its cwd (the manifest handles this via ${CLAUDE_PLUGIN_ROOT} when bundled as a plugin), and you must build the dataset first.

To register it directly in Claude Code without packaging, add the server pointed at your checkout, e.g.:

claude mcp add spudcoach -- uv run --directory /path/to/spud-coach python -m brotato_coach.server

Once connected, just ask in natural language — the model routes your question to the tools below:

• "Does Handcuffs fit my Ranger run? I'm at 7 ranged damage, 65 HP."

• "Minigun T4 vs Revolver T4 at 20 ranged damage — which hits harder?"

• "Is attack speed ever dead weight? Can I let knockback go negative on a gun build?"

• "What does the Ranger's ranged-damage bonus do to a raw stat of 6?"

• "Here's my run.json — how's this build doing?" (post-mortem a whole save at once)

Use with Claude Desktop

Claude Desktop can launch the server with uvx in two forms: fetch straight from this repo (auto-updates on restart, but needs git reachable — see the Windows note below), or point at a local checkout (nothing fetched at runtime; the most reliable form on Windows). Either way you supply your own locally built brotato.json — the dataset is never distributed.

1. Install uv on the machine running Claude Desktop (winget install astral-sh.uv on Windows, or the standalone installer).

2. Open the config file and add the spud-coach server:

   • Windows: %APPDATA%\Claude\claude_desktop_config.json

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

   Fetch-from-repo form:

   {
     "mcpServers": {
       "spud-coach": {
         "command": "uvx",
         "args": [
           "--from", "git+https://github.com/brendanlefebvre/spud-coach",
           "spudcoach",
           "--data", "C:\\Users\\<you>\\path\\to\\brotato.json"
         ]
       }
     }
   }

   Point --data at your built dataset (SPUDCOACH_DATA works as an env-var alternative). On macOS use a POSIX path like /Users/<you>/brotato.json.

3. Fully restart Claude Desktop (quit from the tray, not just close the window).

Windows: "Git executable not found" (or uvx not found)

The git+https://… form makes uv shell out to a git executable. Claude Desktop does not pass your shell — or even your System PATH — to the MCP subprocess; it spawns servers with its own trimmed environment. (The PATH it prints in the logs is its command-resolution list, not what the child process receives.) So a git that runs fine in PowerShell, installed in a System-PATH directory, can still come back "not found" here — and a bare "command": "uvx" can fail to resolve for the same reason. Two fixes:

• Point at a local checkout — no runtime git (recommended). Clone once in a terminal where git works, then use --from <folder> instead of --from git+…:

  git clone https://github.com/brendanlefebvre/spud-coach C:\Users\<you>\src\spud-coach

  {
    "mcpServers": {
      "spud-coach": {
        "command": "uvx",
        "args": ["--from", "C:\\Users\\<you>\\src\\spud-coach", "spudcoach",
                 "--data", "C:\\Users\\<you>\\path\\to\\brotato.json"]
      }
    }
  }

  Update later with git pull in that folder, then restart Desktop.

• Or force the tools onto the server's PATH. Keep the git+https form and add an env block that hands the child an explicit PATH — git, plus uv's bin and the winget-links dir:

  "env": {
    "PATH": "C:\\Program Files\\Git\\cmd;C:\\Users\\<you>\\.local\\bin;C:\\Users\\<you>\\AppData\\Local\\Microsoft\\WinGet\\Links;C:\\Windows\\System32"
  }

  If uvx itself still isn't found, also set "command" to its absolute path (Get-Command uvx to locate it, e.g. C:\Users\<you>\AppData\Local\Microsoft\WinGet\Links\uvx.exe).

Available tools

All tools return a JSON object. Lookups that miss return {"error": "not_found", "did_you_mean": [...]}.

22 tools. Arguments marked ? are optional.

Start here

Data lookups

DPS & comparison

Build evaluation

Bestiary

Run analysis & metadata

Batch lookups. get_weapon, get_item and get_character accept name as either a string or a list of strings. A list returns {"results": [...]} in the order given, each entry a record or its own not_found — so detail on several entities costs one round-trip, not N.

list_characters returns full records, unlike list_weapons / list_items, which return summaries. The whole 50-character corpus is only ~7.7K tokens, so a survey answers in a single call with no follow-up get_character; pass detail="summary" for {id, name} rows instead. Its scaling_stat filter is a derived union — characters have no scaling-stat field — matching a positive stat-gain modifier, a positive flat bonus, or a matching wanted_tag. Each matched record carries a scaling_match object naming which signal fired, e.g. Engineer {"gain_pct": 25, "flat": 10, "wanted": true} vs Technomage {"wanted": true}, so the derivation is visible rather than asserted. Characters penalised in that stat are excluded from the match.

starting_weapon_pool is the run-start weapon-selection pool, not a fixed starting weapon: most characters offer a dozen or more, Arms Dealer offers only the Pistol, and Beast Master and Bull offer none.

stats / current_stats are objects keyed by short stat name (e.g. {"ranged_damage": 7, "max_hp": 65}). names_with_tiers is a list of [name, tier] pairs. path_a / path_b are lists of tier numbers. Note the two stat-name forms: stats / current_stats use the short name (ranged_damage), while the stat argument of explain_stat and stat_display_value uses the stat_-prefixed form (stat_ranged_damage). get_filter_options returns the valid filter values so you don't have to guess (all filters are case-sensitive exact matches).

evaluate_run takes exactly one input: pass the save's contents as run_json (e.g. an uploaded/pasted run.json) or its location as path (e.g. a file in your Brotato save directory). The save is read-only — it is never modified. Ids the loaded dataset doesn't recognize (e.g. content newer than your build) are listed under notes rather than dropped; a malformed save returns {"error": "bad_run_file", ...}.

Building the dataset

The dataset is not committed — it is built from an extraction of a real game install. The raw extracted/, the decompiled recovered/, the copyrighted game_files/, and the derived data/brotato.json are all gitignored (see docs/extraction-setup.md for how the extraction is produced). Once extracted/ is present at the repo root:

uv run python build_dataset.py

This writes data/brotato.json. Game version auto-detects from the decompiled recovered/singletons/progress_data.gd (its VERSION constant), and generated_at defaults to the current UTC time. Pass --game-version <ver> or --generated-at <iso8601> explicitly to override either — e.g. if recovered/ isn't present, or to pin a reproducible value for a test or release script. Re-run after each patch to refresh your local copy — it stays gitignored, so don't commit it.

How it works

extracted/  (gitignored, regenerable)          raw .tres game data
     │
     ▼   build_dataset.py   (offline, per patch)
data/brotato.json  (gitignored, built locally)  the deterministic core artifact
     │
     ▼   loaded at startup
brotato_coach.server (FastMCP)                  16 tools over the pure functions
     │
     ▼   connected as a plugin
Claude Code / Desktop / Web                     chat frontend

• brotato_coach/tres.py — a minimal Godot .tres parser.

• brotato_coach/builders/ — turn parsed .tres into enriched records (weapons with precomputed DPS lines, items with archetype flags, characters with gain modifiers, sets, and the verified stat_mechanics table).

• brotato_coach/calc.py — pure DPS / merge math (no I/O), unit-tested against hand-verified values.

• brotato_coach/{query,answers,evaluate}.py — pure functions that produce finished answers.

• brotato_coach/runfile.py — pure parser that normalizes a Brotato run.json save into a build (character, weapons, items, realized stats) for evaluate_run; the only I/O is reading the save file.

• brotato_coach/server.py — thin FastMCP wrappers over those functions.

Reference material on the game mechanics the coach encodes lives in docs/ (extraction setup, weapon-merge DPS methodology, run post-mortem methodology, stat mechanics).

Disclaimer

This is an unofficial, fan-made tool. It is not affiliated with, endorsed by, or sponsored by Blobfish, the developer of Brotato, or any of its partners. Brotato and all related names, marks, and assets are the property of their respective owners.

This project ships no game assets and no game data. The stat dataset it operates on is generated locally, by you, from a copy of the game you already own (build_dataset.py reads an extraction of your own install). Nothing derived from the game's copyrighted files is distributed in this repository.

The software is provided "as is", without warranty of any kind (see LICENSE). Its recommendations are computed from datamined values and may be incomplete or wrong; use your own judgment.

License

MIT © 2026 Brendan LeFebvre. This license covers the code and documentation in this repository only — it does not grant any rights to Brotato or its assets.