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dmang-dev

mcp-dolphin

dolphin_write16

Write a 16-bit big-endian value to PowerPC memory for game cheats like HP or scores. Requires 2-byte aligned address.

Instructions

PURPOSE: Write an unsigned 16-bit big-endian value to PowerPC memory. USAGE: For 16-bit cheats/pokes (HP, score, coordinates). For single bytes use dolphin_write8; for 32/64-bit use dolphin_write32/write64. The value is byte-swapped to big-endian by Felk's bridge — pass the value the game logically sees, not its byte order. BEHAVIOR: DESTRUCTIVE: overwrites two bytes with no undo. Address MUST be 2-byte aligned. Returns an error on bridge disconnect or FAIL.

GameCube + Wii main address space landmarks (PowerPC, big-endian): 0x80000000-0x817FFFFF MEM1 main RAM (24 MiB) — GameCube + Wii game code & data GameCube games stay entirely within MEM1. Wii games use MEM1 for code and frequently-accessed data. 0x80000020 OS_GLOBALS — game-info struct (disc ID, FST, etc.) 0x80000034 OS_ARENA_LO (start of free MEM1 heap) 0x80003100 OS_REPORT (developer-console mirror, varies by SDK) 0x90000000-0x93FFFFFF MEM2 (64 MiB) — Wii ONLY. Larger texture/asset data, IOS work areas. Reading MEM2 on a GameCube game returns garbage / FAIL. 0xCC000000-0xCC00FFFF Hollywood I/O (Wii) / Flipper I/O (GameCube) — DMA, GPU FIFO, AI, EXI registers. Reads are usually safe, writes can wedge the emulator. Avoid. 0xCD000000-0xCD007FFF Wii-only Hollywood registers.

Notes: • All multi-byte values are BIG-ENDIAN on the real hardware. Felk's memory.read_u*/write_u* helpers handle the byte swap for you — the value you see is the value the game sees as a u32. • Addresses are 32-bit; Felk truncates the high bits of any u64 address argument. • Pointers in MEM1 are often stored as 4-byte addresses with the high bit set (e.g. 0x81234567). Dereferencing them requires no masking — pass the raw value back into memory.read_*.

RETURNS: 'Wrote VAL_DEC (0xVAL_HEX) → ADDR_HEX'.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
addressYesAbsolute PowerPC virtual address (0x80000000-0x9FFFFFFF). Pass as a number; hex literals like 0x80001000 are fine. Reads 2 consecutive bytes starting here and interprets them as a big-endian value. MUST be 2-byte aligned (address % 2 === 0). PowerPC raises an alignment exception on misaligned access in hardware, but Dolphin's emulated bus is forgiving and silently returns the aligned-down word — i.e. you get the bytes from address & ~1, not what you asked for. For unaligned multi-byte reads use dolphin_read_range and assemble client-side. Useful ranges: 0x80000000-0x817FFFFF for MEM1 (GC + Wii), 0x90000000-0x93FFFFFF for MEM2 (Wii only).
valueYes16-bit value (0-65535 / 0x0000-0xFFFF). For signed values, encode as two's complement (e.g. -1 → 0xFFFF).
Behavior5/5

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

No annotations exist, so the description fully covers behavior. It states it is destructive with no undo, mentions error conditions on bridge disconnect, explains byte swapping, and provides extensive memory layout details. This is thorough and transparent.

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?

The description is well-structured with clear sections (Purpose, Usage, Behavior) and front-loaded with key information. It is lengthy due to a detailed memory map, but each part is useful and earned its place. Slightly verbose, but justified.

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?

Given the complexity and absence of an output schema, the description covers return format, errors, alignment, byte ordering, and memory ranges. It provides all necessary context for an agent to use the tool correctly.

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 schema already explains alignment, ranges, and signed encoding. The description adds context about byte swapping and big-endian handling, but doesn't significantly enhance parameter semantics beyond what the schema provides. Baseline of 3 is appropriate.

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?

The description explicitly states the purpose as writing an unsigned 16-bit big-endian value to PowerPC memory. It clearly identifies the verb (write) and resource (16-bit value), and distinguishes from sibling tools by mentioning alternatives for other sizes.

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

Usage Guidelines5/5

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

The description provides explicit usage guidance for 16-bit cheats/pokes and directs to sibling tools for other sizes. It also notes alignment requirements and byte swapping, giving clear context for when to use this tool.

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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