refactor(skill-mcp): split tools.ts to comply with 200 LOC module rule

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/tools/skill-mcp/parse-skill-mcp-arguments.ts

@@ -0,0 +1,25 @@
+export function parseSkillMcpArguments(
+  argsJson: string | Record<string, unknown> | undefined,
+): Record<string, unknown> {
+  if (!argsJson) return {}
+  if (typeof argsJson === "object" && argsJson !== null) {
+    return argsJson
+  }
+
+  try {
+    const jsonString = argsJson.startsWith("'") && argsJson.endsWith("'") ? argsJson.slice(1, -1) : argsJson
+    const parsed = JSON.parse(jsonString)
+    if (typeof parsed !== "object" || parsed === null) {
+      throw new Error("Arguments must be a JSON object")
+    }
+
+    return parsed as Record<string, unknown>
+  } catch (error) {
+    const errorMessage = error instanceof Error ? error.message : String(error)
+    throw new Error(
+      `Invalid arguments JSON: ${errorMessage}\n\n` +
+        `Expected a valid JSON object, e.g.: '{"key": "value"}'\n` +
+        `Received: ${argsJson}`,
+    )
+  }
+}

src/tools/skill-mcp/tools.ts

@@ -1,6 +1,7 @@
 import { tool, type ToolDefinition } from "@opencode-ai/plugin"
 import type { ToolContext } from "@opencode-ai/plugin/tool"
 import { BUILTIN_MCP_TOOL_HINTS, SKILL_MCP_DESCRIPTION } from "./constants"
+import { parseSkillMcpArguments } from "./parse-skill-mcp-arguments"
 import type { SkillMcpArgs } from "./types"
 import type { SkillMcpManager, SkillMcpClientInfo, SkillMcpServerContext } from "../../features/skill-mcp-manager"
 import type { LoadedSkill } from "../../features/opencode-skill-loader/types"
@@ -82,30 +83,6 @@ function formatBuiltinMcpHint(mcpName: string): string | null {
   )
 }
 
-function parseArguments(argsJson: string | Record<string, unknown> | undefined): Record<string, unknown> {
-  if (!argsJson) return {}
-  if (typeof argsJson === "object" && argsJson !== null) {
-    return argsJson
-  }
-  try {
-    // Strip outer single quotes if present (common in LLM output)
-    const jsonStr = argsJson.startsWith("'") && argsJson.endsWith("'") ? argsJson.slice(1, -1) : argsJson
-
-    const parsed = JSON.parse(jsonStr)
-    if (typeof parsed !== "object" || parsed === null) {
-      throw new Error("Arguments must be a JSON object")
-    }
-    return parsed as Record<string, unknown>
-  } catch (error) {
-    const errorMessage = error instanceof Error ? error.message : String(error)
-    throw new Error(
-      `Invalid arguments JSON: ${errorMessage}\n\n` +
-        `Expected a valid JSON object, e.g.: '{"key": "value"}'\n` +
-        `Received: ${argsJson}`,
-    )
-  }
-}
-
 export function applyGrepFilter(output: string, pattern: string | undefined): string {
   if (!pattern) return output
   try {
@@ -174,7 +151,7 @@ export function createSkillMcpTool(options: SkillMcpToolOptions): ToolDefinition
         skillName: found.skill.name,
       }
 
-      const parsedArgs = parseArguments(args.arguments)
+      const parsedArgs = parseSkillMcpArguments(args.arguments)
 
       let output: string
       switch (operation.type) {