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mcp-ppsspp

by dmang-dev
OverviewSchemaRelated ServersScoreDiscussions
TypeScript
Hybrid

ppsspp_breakpoint_list

Lists all currently-set CPU execution breakpoints to allow inventory prior to bulk removal or sanity-check of what is set.

Instructions

PURPOSE: List all currently-set CPU execution breakpoints. USAGE: Inventory before bulk-removing, or sanity-check what's set. BEHAVIOR: No side effects — pure read. RETURNS: Multi-line text, one line per breakpoint with its address and any conditions.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Implementation Reference

  • src/tools.ts:601-607 (handler)
    Handler for ppsspp_breakpoint_list: calls PPSSPP's cpu.breakpoint.list via WebSocket and formats the response showing all breakpoint addresses, disabled status, and conditions.
    case "ppsspp_breakpoint_list": {
  const r = await pp.call<{ breakpoints?: Array<{ address: number; enabled?: boolean; condition?: string }> }>("cpu.breakpoint.list");
  const bps = r.breakpoints ?? [];
  if (bps.length === 0) return ok("No breakpoints set.");
  const lines = bps.map((b) => `  ${addrHex(b.address)} ${b.enabled === false ? "(disabled)" : ""}${b.condition ? ` if ${b.condition}` : ""}`);
  return ok(`${bps.length} breakpoint${bps.length === 1 ? "" : "s"}:\n${lines.join("\n")}`);
}
  • src/tools.ts:383-391 (schema)
    Tool definition/schema for ppsspp_breakpoint_list with description and empty inputSchema (no params required).
    {
  name: "ppsspp_breakpoint_list",
  description:
    "PURPOSE: List all currently-set CPU execution breakpoints. " +
    "USAGE: Inventory before bulk-removing, or sanity-check what's set. " +
    "BEHAVIOR: No side effects — pure read. " +
    "RETURNS: Multi-line text, one line per breakpoint with its address and any conditions.",
  inputSchema: { type: "object", properties: {} },
},
  • src/tools.ts:405-613 (registration)
    registerTools registers all tools via Server.setRequestHandler for ListToolsRequestSchema and CallToolRequestSchema, routing tool calls by name in a switch/case block.
    export function registerTools(server: Server, pp: PpssppClient): void {
  server.setRequestHandler(ListToolsRequestSchema, async () => ({ tools: TOOLS }));

  server.setRequestHandler(CallToolRequestSchema, async (req) => {
    const { name, arguments: args = {} } = req.params;
    const p = args as Record<string, unknown>;
    const a = () => p.address as number;

    switch (name) {
      case "ppsspp_ping": {
        const r = await pp.call<{ version?: string; name?: string }>("version");
        return ok(`pong (${r.name ?? "PPSSPP"} ${r.version ?? "(unknown version)"})`);
      }

      case "ppsspp_get_info": {
        const status = await pp.call<{ game?: { id?: string; title?: string; version?: string } | null; paused?: boolean; stepping?: boolean }>("game.status");
        const lines: string[] = [];
        if (status.game) {
          lines.push(`Title:   ${status.game.title ?? "(unavailable)"}`);
          lines.push(`Disc ID: ${status.game.id ?? "(unavailable)"}`);
          lines.push(`Version: ${status.game.version ?? "(unavailable)"}`);
        } else {
          lines.push("No game loaded.");
        }
        const state = status.stepping ? "stepping (paused)" : status.paused ? "paused" : "running";
        lines.push(`State:   ${state}`);
        return ok(lines.join("\n"));
      }

      case "ppsspp_read8": {
        const r = await pp.call<{ value: number }>("memory.read_u8", { address: a() });
        return ok(`${addrHex(a())}: ${fmtHex(r.value)}`);
      }
      case "ppsspp_read16": {
        const r = await pp.call<{ value: number }>("memory.read_u16", { address: a() });
        return ok(`${addrHex(a())}: ${fmtHex(r.value)}`);
      }
      case "ppsspp_read32": {
        const r = await pp.call<{ value: number }>("memory.read_u32", { address: a() });
        return ok(`${addrHex(a())}: ${fmtHex(r.value)}`);
      }
      case "ppsspp_read_range": {
        const r = await pp.call<{ base64: string }>("memory.read", { address: a(), size: p.size });
        const bytes = Buffer.from(r.base64 ?? "", "base64");
        const hex = Array.from(bytes).map((b) => b.toString(16).padStart(2, "0").toUpperCase()).join(" ");
        return ok(`${addrHex(a())} [${bytes.length} bytes]:\n${hex}`);
      }
      case "ppsspp_read_string": {
        const r = await pp.call<{ value: string }>("memory.readString", { address: a(), type: "utf-8" });
        return ok(`${addrHex(a())}: ${JSON.stringify(r.value ?? "")}`);
      }

      case "ppsspp_write8": {
        await pp.call("memory.write_u8", { address: a(), value: p.value });
        return ok(`Wrote ${fmtHex(p.value)} → ${addrHex(a())}`);
      }
      case "ppsspp_write16": {
        await pp.call("memory.write_u16", { address: a(), value: p.value });
        return ok(`Wrote ${fmtHex(p.value)} → ${addrHex(a())}`);
      }
      case "ppsspp_write32": {
        await pp.call("memory.write_u32", { address: a(), value: p.value });
        return ok(`Wrote ${fmtHex(p.value)} → ${addrHex(a())}`);
      }
      case "ppsspp_write_range": {
        const bytes = Buffer.from(p.bytes as number[]);
        const base64 = bytes.toString("base64");
        await pp.call("memory.write", { address: a(), base64 });
        return ok(`Wrote ${bytes.length} bytes → ${addrHex(a())}`);
      }

      case "ppsspp_press_buttons": {
        await pp.call("input.buttons.send", { buttons: p.buttons });
        const pressed = Object.entries(p.buttons as Record<string, boolean>)
          .filter(([, v]) => v).map(([k]) => k);
        return ok(`Set buttons: ${pressed.length ? pressed.join("+") : "(all released)"}`);
      }
      case "ppsspp_press_button": {
        await pp.call("input.buttons.press", { button: p.button, duration: p.duration ?? 1 });
        return ok(`Pressed ${p.button} for ${p.duration ?? 1} frames (auto-released)`);
      }
      case "ppsspp_send_analog": {
        await pp.call("input.analog.send", { stick: p.stick, x: p.x, y: p.y });
        return ok(`Set analog stick ${p.stick} to (${p.x}, ${p.y})`);
      }

      case "ppsspp_pause": {
        // cpu.stepping is fire-and-forget per PPSSPP source ("No immediate
        // response. Once CPU is stepping, a 'cpu.stepping' event will be
        // sent."). Send it, then poll cpu.status until stepping=true.
        await pp.fireAndForget("cpu.stepping");
        await pp.waitForState((s) => s.stepping === true);
        return ok("Emulation paused");
      }
      case "ppsspp_resume": {
        await pp.fireAndForget("cpu.resume");
        await pp.waitForState((s) => s.stepping === false);
        return ok("Emulation resumed");
      }
      case "ppsspp_step": {
        const r = await pp.call<{ pc?: number }>("cpu.stepInto");
        return ok(`Stepped one instruction. PC: ${r.pc !== undefined ? addrHex(r.pc) : "(unknown)"}`);
      }
      case "ppsspp_reset": {
        await pp.call("game.reset");
        return ok("Game reset");
      }
      case "ppsspp_screenshot": {
        // PPSSPP's gpu.buffer.* events all require CORE_STEPPING_CPU (or GPU
        // stepping) state — they fail with "Neither CPU or GPU is stepping"
        // otherwise. We transparently pause→capture→resume so callers can
        // screenshot any time without managing pause state. If the emulator
        // was already paused, we leave it paused.
        //
        // source='render' (default) uses gpu.buffer.renderColor → reads the
        // active GPU render target. Safer: GPU_GetCurrentFramebuffer hits a
        // different code path than the crash-prone GPU_GetOutputFramebuffer.
        //
        // source='output' uses gpu.buffer.screenshot → reads the final
        // composited output (what's on screen, post scaling/shaders). Can
        // CRASH PPSSPP on some games: upstream has an `_assert_(buf != nullptr)`
        // after GPU_GetOutputFramebuffer that fires when the function returns
        // true with a null buffer (observed on some homebrew). We can't catch
        // a process abort from outside, but v0.1.2's auto-reconnect means MCP
        // recovers when PPSSPP is relaunched.
        const source = (p.source as string | undefined) ?? "render";
        const event  = source === "output" ? "gpu.buffer.screenshot" : "gpu.buffer.renderColor";
        const statusBefore = await pp.call<{ stepping?: boolean; paused?: boolean }>("cpu.status");
        const wasStepping = !!statusBefore.stepping;
        if (!wasStepping) {
          await pp.fireAndForget("cpu.stepping");
          await pp.waitForState((s) => s.stepping === true);
        }
        try {
          // type: "base64" returns the raw base64 payload; the default "uri"
          // returns a "data:image/png;base64,..." prefix which we'd have to strip.
          const r = await pp.call<{ base64?: string; uri?: string }>(event, { type: "base64" });
          let b64 = r.base64;
          if (!b64 && r.uri) {
            // Belt-and-suspenders: if PPSSPP returned a URI anyway, strip the prefix.
            const m = /^data:image\/png;base64,(.*)$/.exec(r.uri);
            if (m) b64 = m[1];
          }
          if (!b64) {
            throw new Error(`PPSSPP did not return screenshot data from ${event} (no game loaded, or framebuffer not readable?)`);
          }
          return {
            content: [
              { type: "text" as const, text: `Screenshot captured (source: ${source}, event: ${event}).` },
              { type: "image" as const, data: b64, mimeType: "image/png" },
            ],
          };
        } finally {
          if (!wasStepping) {
            try {
              await pp.fireAndForget("cpu.resume");
              await pp.waitForState((s) => s.stepping === false, { timeoutMs: 2000 });
            } catch { /* best-effort */ }
          }
        }
      }

      case "ppsspp_get_registers": {
        // PPSSPP's cpu.getAllRegs returns categories with PARALLEL arrays:
        //   { categories: [{ name, registerNames: [...], uintValues: [...], floatValues: [...] }] }
        // Not an array of {name, value} objects as I first assumed.
        const r = await pp.call<{
          categories?: Array<{
            name: string;
            registerNames?: string[];
            uintValues?: number[];
            floatValues?: string[];
          }>;
        }>("cpu.getAllRegs");
        const lines: string[] = [];
        for (const cat of r.categories ?? []) {
          lines.push(`── ${cat.name} ──`);
          const names = cat.registerNames ?? [];
          const vals  = cat.uintValues ?? [];
          for (let i = 0; i < Math.max(names.length, vals.length); i++) {
            const nm = names[i] ?? `r${i}`;
            const v  = vals[i];
            lines.push(`  ${nm.padEnd(8)} = ${v !== undefined ? addrHex(v) : "(unavailable)"}`);
          }
        }
        return ok(lines.join("\n") || "(no registers returned)");
      }

      case "ppsspp_breakpoint_add": {
        await pp.call("cpu.breakpoint.add", { address: a() });
        return ok(`Breakpoint added at ${addrHex(a())}`);
      }
      case "ppsspp_breakpoint_remove": {
        await pp.call("cpu.breakpoint.remove", { address: a() });
        return ok(`Breakpoint removed at ${addrHex(a())}`);
      }
      case "ppsspp_breakpoint_list": {
        const r = await pp.call<{ breakpoints?: Array<{ address: number; enabled?: boolean; condition?: string }> }>("cpu.breakpoint.list");
        const bps = r.breakpoints ?? [];
        if (bps.length === 0) return ok("No breakpoints set.");
        const lines = bps.map((b) => `  ${addrHex(b.address)} ${b.enabled === false ? "(disabled)" : ""}${b.condition ? ` if ${b.condition}` : ""}`);
        return ok(`${bps.length} breakpoint${bps.length === 1 ? "" : "s"}:\n${lines.join("\n")}`);
      }

      default:
        throw new Error(`Unknown tool: ${name}`);
    }
  });
}
  • src/ppsspp.ts:235-271 (helper)
    PpssppClient.call() method used to send the 'cpu.breakpoint.list' RPC to PPSSPP over WebSocket and await a ticketed response.
    async call<T extends Record<string, unknown> = Record<string, unknown>>(
  event: string,
  params: Record<string, unknown> = {},
): Promise<T> {
  // Auto-(re)connect on demand. PPSSPP can be launched, closed, relaunched
  // at any point during the MCP server's lifetime; ensureConnected() will
  // bring the socket back up (or throw a clear error if PPSSPP isn't
  // reachable). Without this, a single failed connect at MCP boot would
  // leave every subsequent tool call broken until MCP-client restart.
  await this.ensureConnected();
  return new Promise<T>((resolve, reject) => {
    const ticket = `t${this.nextTicket++}`;
    const pending: PendingCmd = {
      ticket,
      resolve: (r) => resolve(r as T),
      reject,
    };

    const timer = setTimeout(() => {
      this.inflight.delete(ticket);
      reject(new Error(
        `PPSSPP call "${event}" timed out (${this.timeoutMs}ms) — ` +
        `is PPSSPP running with "Allow remote debugger" enabled?`,
      ));
    }, this.timeoutMs);
    const origResolve = pending.resolve, origReject = pending.reject;
    pending.resolve = (r) => { clearTimeout(timer); origResolve(r); };
    pending.reject  = (e) => { clearTimeout(timer); origReject(e); };

    this.inflight.set(ticket, pending);
    const msg = JSON.stringify({ event, ticket, ...params });
    if (process.env.MCP_PPSSPP_DEBUG) {
      process.stderr.write(`[trace] TX: ${msg}\n`);
    }
    this.ws!.send(msg);
  });
}

Tool Definition Quality

A4.6/5.0
Behavior5/5

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

Declares 'BEHAVIOR: No side effects — pure read.' Without annotations, the description fully covers behavioral traits, assuring the agent of safe, read-only operation.

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 section headers (PURPOSE, USAGE, BEHAVIOR, RETURNS). Each of the four sentences serves a distinct purpose without redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple list tool with no parameters and no output schema, the description covers purpose, usage, behavior, and return format. Could mention sibling distinction, but overall sufficient.

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?

Input schema has zero parameters (100% coverage). Description adds no parameter details, but no parameters exist. Baseline of 4 for zero-parameter case is appropriate.

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 explicitly states 'List all currently-set CPU execution breakpoints', using specific verb and resource. Clearly distinguishes from sibling tools like ppsspp_breakpoint_add and ppsspp_breakpoint_remove.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit when-to-use instructions: 'Inventory before bulk-removing, or sanity-check what's set.' While no explicit alternatives or when-not-to, the context makes it clear it's for listing only.

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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