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dmang-dev

mcp-retroarch

retroarch_frame_advance

Step emulation forward one frame at a time while paused. Use for precise input timing, animation inspection, or letting emulation initialize after a reset.

Instructions

PURPOSE: Step emulation forward by exactly one frame. USAGE: Use for frame-precise input automation, animation inspection, or letting the system initialize after a reset. ONLY effective while emulation is paused — RetroArch's FRAMEADVANCE is a no-op when running, so call retroarch_pause_toggle first (after checking retroarch_get_status to confirm you'll end up paused, not unpaused). For long jumps (thousands of frames) prefer retroarch_save_state_current / retroarch_load_state_current of a pre-prepared state — frame-by-frame stepping costs ~1 UDP round-trip per frame. BEHAVIOR: When paused, advances the emulator by exactly one frame and remains paused. When NOT paused, the command is silently ignored by RetroArch. 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. The new frame count is not reported — to verify progress, take screenshots before/after with retroarch_screenshot or read a known-changing memory value. 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 'Advanced one frame' (UDP-send confirmation only — does NOT confirm that RetroArch was paused or that the frame actually advanced).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Behavior5/5

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

Describes behavior when paused vs unpaused, fire-and-forget nature, no confirmation, UDP silent drops, and need for verification. No annotations so description carries full burden.

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?

Well-structured with labeled sections, front-loaded purpose. Slightly verbose but every sentence adds value.

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?

Covers purpose, usage, prerequisites, failure modes, transport, return value, and verification steps. Complete for a no-param tool with no output schema.

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?

No parameters; schema coverage 100%. Description adds no param info but baseline for 0 params is 4.

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?

Description clearly states 'Step emulation forward by exactly one frame' with specific verb and resource, distinguishing it from sibling tools like pause toggle and reset.

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 tells when to use (frame-precise tasks) and when not (long jumps prefer save/load), with prerequisite to ensure paused state and reference to sibling tools.

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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