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bizhawk_save_state

Save the entire emulator state to a file for rollback points, game state bookmarks, or repro sharing. Overwrites existing files without backup.

Instructions

PURPOSE: Save the entire emulator state (RAM, CPU/PPU/APU registers, mapper state, sound chip state, timing) to a file at the given path. USAGE: Use as a rollback point before risky writes, to bookmark interesting game states, or to share repro states. The companion bizhawk_load_state can perfectly restore from this file. BizHawk's savestate API is path-based (NOT slot-based like mGBA's). BEHAVIOR: DESTRUCTIVE TO TARGET FILE: overwrites the file at path if it exists, with no prompt or backup. The state file is bound to the EXACT ROM and BizHawk core version that produced it — loading it on a different ROM or core version usually crashes the core. Returns an error if the parent directory doesn't exist, the path isn't writable, or the core doesn't expose savestate.save. RETURNS: Single line 'Saved state to PATH'.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
pathYesAbsolute filesystem path to write the .State file to (extension is convention, not required). Parent directory must exist. File is overwritten without prompt if present.
Behavior5/5

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

Despite no annotations, the description fully discloses destructive behavior (overwrites without prompt), compatibility constraints (bound to exact ROM and core version), and error conditions (parent directory missing, unwritable path, core not supporting save).

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?

The description is well-structured with clear sections (PURPOSE, USAGE, BEHAVIOR, RETURNS). Every sentence is informative and necessary, none wasted.

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 single-parameter tool without output schema, the description is complete. It covers output format, error conditions, and critical behavioral details like version binding, leaving no gaps.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, but the description adds significant value: clarifies that extension is convention not required, parent directory must exist, and file is overwritten without prompt. This context goes beyond the schema's property description.

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 verb 'save', the resource 'entire emulator state', and the target 'file at given path'. It distinguishes itself from the sibling 'bizhawk_load_state' by explicitly mentioning the companion tool for restoration.

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 scenarios: 'rollback point before risky writes', 'bookmark interesting game states', 'share repro states'. It also differentiates from slot-based systems by noting BizHawk's path-based API.

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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