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dmang-dev

mcp-retroarch

retroarch_save_state_current

Save the emulator state to RetroArch's currently selected save slot for creating rollback points or bookmarking game states.

Instructions

PURPOSE: Save the entire emulator state to RetroArch's currently-selected save slot (one of slots 0-9). USAGE: Use as a rollback point before risky writes, to bookmark interesting game states, or to share repro states. RetroArch's NCI has NO 'save to slot N' command — to target a specific slot, you must first walk the slot pointer there with retroarch_state_slot_plus / retroarch_state_slot_minus, then call this. The current slot is RetroArch's internal state and is NOT reported back by the NCI, so if you don't track it yourself, observe the on-screen slot indicator after each plus/minus or use retroarch_show_message as a confirmation echo. The companion retroarch_load_state_current restores from the same slot. For path-based savestate I/O (no slots), there is no NCI equivalent — use the BizHawk or mGBA MCP servers instead. BEHAVIOR: DESTRUCTIVE TO TARGET SLOT FILE: overwrites whatever was previously in the currently-selected slot with no prompt or backup. The state file lands in RetroArch's configured savestate_directory (queryable via retroarch_get_config). State files are bound to the EXACT ROM and core version that produced them — loading on a different ROM or core typically fails. FIRE-AND-FORGET: the NCI does NOT acknowledge this command — the call returns as soon as the UDP datagram is sent, with no confirmation that RetroArch received or applied it. To verify the effect, follow up with an observable tool (retroarch_get_status for run state, retroarch_read_memory / retroarch_read_ram for memory mutations, retroarch_screenshot for visual state). UDP packets to a not-listening RetroArch are silently dropped. To verify the save happened, retroarch_load_state_current it back and observe via memory-read or screenshot. Transport: RetroArch's Network Control Interface (NCI) over UDP (default 127.0.0.1:55355, requires network_cmd_enable = true in retroarch.cfg). RETURNS: Single line 'Saved to current slot' (UDP-send confirmation only — does NOT verify the file was written, nor report which slot number it landed in).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

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 slot file), fire-and-forget nature (no confirmation), UDP silent drops, and state file ROM/core binding. It also explains transport and return value limitations. This is exceptionally 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 lengthy but well-structured with labeled sections (PURPOSE, USAGE, BEHAVIOR, TRANSPORT, RETURNS). Every sentence adds value, though some redundancy could be trimmed. Still, it is effectively organized and front-loaded.

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 no parameters and no output schema, the description covers all necessary context: purpose, usage context, behavioral caveats, transport details, and return value. It references sibling tools and explains limitations, making it fully self-contained.

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?

The input schema has zero parameters (100% coverage). The description explains why no parameters are needed (saves to current slot), adding context beyond the schema. A score of 4 is appropriate as the baseline is 4 for zero-parameter tools.

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 action ('Save the entire emulator state'), the target resource ('RetroArch's currently-selected save slot'), and distinguishes from siblings like retroarch_load_state_current and slot navigation tools. The scope is specific and unambiguous.

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 describes when to use (rollback, bookmarking, repro states) and when not to use, with clear alternatives: path-based I/O requires BizHawk/mGBA, targeting a specific slot requires prior slot pointer manipulation. The guidance is comprehensive and actionable.

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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