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dmang-dev

mcp-retroarch

retroarch_load_state_slot

Load a save state from a numbered slot without altering RetroArch's current-slot pointer. Use to access specific bookmarks while preserving ongoing save location.

Instructions

PURPOSE: Load state from an explicitly-named save slot number, without modifying RetroArch's currently-selected slot pointer. USAGE: Use to load from a specific slot when you don't want to disturb the current-slot pointer (e.g. you're alternating between two bookmarks while keeping the 'live' slot for ongoing saves). For loading from the currently-selected slot, use retroarch_load_state_current — semantically distinct: this tool ignores the current-slot pointer entirely and addresses by number. Slots are numbered 0-9 by RetroArch convention. There is no retroarch_save_state_slot counterpart in the NCI — saving to a specific slot still requires walking the pointer with state_slot_plus/minus and then calling save_state_current. BEHAVIOR: DESTRUCTIVE TO LIVE STATE: replaces ALL current emulator state with the named slot's contents. Anything not previously snapshotted is lost. The state file MUST come from the same ROM and core version that produced it. Transport: RetroArch's Network Control Interface (NCI) over UDP (default 127.0.0.1:55355, requires network_cmd_enable = true in retroarch.cfg). UNLIKE most NCI control commands, LOAD_STATE_SLOT does send a reply (this client awaits it), so a UDP timeout will surface as an error here even though sibling load/save calls are fire-and-forget. If the named slot has no saved state, RetroArch's reply still indicates the command was processed — verify with a memory-read or screenshot. The current-slot pointer is unchanged after this call. RETURNS: Single line 'Loaded from slot N' echoing the requested slot number.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
slotYesSave state slot number to load from. RetroArch's standard slot range is 0-9 (ten slots), but the NCI does not enforce a hard upper bound — slot numbers outside the configured range will simply find no file and silently no-op. This call does NOT change the currently-selected slot pointer (use retroarch_state_slot_plus / retroarch_state_slot_minus for that).
Behavior5/5

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

With no annotations, the description fully discloses behavioral traits: 'DESTRUCTIVE TO LIVE STATE: replaces ALL current emulator state... Anything not previously snapshotted is lost.' It also covers transport requirements, reply behavior vs. siblings, error handling (UDP timeout), and constraints on state file compatibility.

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 labeled sections (PURPOSE, USAGE, BEHAVIOR, RETURNS). It is front-loaded with purpose and usage, every sentence adds distinct value, and there is no redundancy despite comprehensive coverage.

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 of the tool (emulator state manipulation, no output schema), the description is remarkably complete. It explains return value format, error conditions (UDP timeout, missing state file), transport details, and dependencies (same ROM/core). No obvious gaps remain.

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% for the single parameter 'slot'. The description adds meaning beyond the schema by noting standard range (0-9), that the NCI doesn't enforce upper bound, that out-of-range slots silently no-op, and that the call does not change the current-slot pointer.

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 'PURPOSE: Load state from an explicitly-named save slot number, without modifying RetroArch's currently-selected slot pointer.' This clearly identifies the verb (load), resource (save slot), and behavior (no pointer change), differentiating it from sibling retroarch_load_state_current.

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: 'Use to load from a specific slot when you don't want to disturb the current-slot pointer... For loading from the currently-selected slot, use retroarch_load_state_current — semantically distinct.' It clearly states when to use this tool and when to use an alternative.

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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