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bizhawk_write32

Write a 32-bit little-endian value to emulator memory for cheats and pokes. Overwrites four bytes at the specified address with no undo; save state first if rollback needed.

Instructions

PURPOSE: Write an unsigned 32-bit little-endian value to emulator memory at the given address. USAGE: Use for 32-bit cheats and pokes (timestamps, large counters, pointers on 32-bit systems). For 8/16-bit values use bizhawk_write8/write16; for big-endian layouts byteswap and use bizhawk_write_range. BEHAVIOR: DESTRUCTIVE: overwrites four bytes starting at address with no undo (snapshot via bizhawk_save_state first if you need rollback). Direct memory write — bypasses MBC/mapper/DMA, see bizhawk_write8 notes. Returns an error if the domain is unknown, address+4 exceeds the domain, value < 0 or > 4294967295, or the core lacks memory.write_u32_le. RETURNS: Single line 'Wrote VAL_DEC (0xVAL_HEX) → ADDR_HEX (DOMAIN)'.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
addressYesByte offset within the chosen memory domain. Per-domain offsets are 0-based and INDEPENDENT of system bus addresses (e.g. SNES WRAM uses 0x09C6, NOT 0x7E09C6). Reads 4 consecutive bytes starting here. Returns an error if address < 0 or address + 4 exceeds the domain's size.
valueYes32-bit value to write. Must be 0-4294967295 (0x00000000-0xFFFFFFFF). LSB lands at `address`, MSB at `address+3`. Values outside this range return an error.
domainNoOptional case-sensitive memory domain name. Omit to use BizHawk's currently selected domain (see bizhawk_get_info → current_memory_domain). Discover available names with bizhawk_list_memory_domains; they vary per system (WRAM on SNES, RAM on NES, RDRAM on N64, 68K RAM on Genesis, MainRAM on PSX, EWRAM/IWRAM on GBA). Returns an error if the name doesn't match any domain on the loaded core.
Behavior5/5

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

With no annotations, the description fully discloses destructive behavior (overwrites four bytes, no undo), error conditions, and that it bypasses MBC/mapper/DMA. Provides actionable guidance (save state first).

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?

Well-structured with clear headings (PURPOSE, USAGE, BEHAVIOR, RETURNS). Every sentence is informative and front-loaded with purpose. No wasted words.

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?

Comprehensive coverage of purpose, usage, behavior, error conditions, and return format. Schema handles parameter details, leaving description to address agent decision-making needs fully.

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% with detailed descriptions. The tool description adds practical usage examples (timestamps, large counters) and reinforces error conditions, but does not add significant new semantic detail beyond what schema already provides.

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 clearly states the tool writes a 32-bit little-endian value to emulator memory. It distinguishes from siblings like bizhawk_write8 and bizhawk_write16 by specifying bit width and endianness.

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?

Explicitly recommends use for 32-bit cheats and pokes, and advises using alternative tools for 8/16-bit values or big-endian layouts. Includes when to avoid (e.g., need for rollback) and suggests snapshotting.

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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