core: refactor tool system to remove agent context from initialization (#21052)

packages/opencode/src/tool/skill.ts

@@ -1,3 +1,4 @@
+import { Effect } from "effect"
 import path from "path"
 import { pathToFileURL } from "url"
 import z from "zod"
@@ -6,8 +7,12 @@ import { Skill } from "../skill"
 import { Ripgrep } from "../file/ripgrep"
 import { iife } from "@/util/iife"
 
-export const SkillTool = Tool.define("skill", async (ctx) => {
-  const list = await Skill.available(ctx?.agent)
+const Parameters = z.object({
+  name: z.string().describe("The name of the skill from available_skills"),
+})
+
+export const SkillTool = Tool.define("skill", async () => {
+  const list = await Skill.available()
 
   const description =
     list.length === 0
@@ -27,20 +32,10 @@ export const SkillTool = Tool.define("skill", async (ctx) => {
           Skill.fmt(list, { verbose: false }),
         ].join("\n")
 
-  const examples = list
-    .map((skill) => `'${skill.name}'`)
-    .slice(0, 3)
-    .join(", ")
-  const hint = examples.length > 0 ? ` (e.g., ${examples}, ...)` : ""
-
-  const parameters = z.object({
-    name: z.string().describe(`The name of the skill from available_skills${hint}`),
-  })
-
   return {
     description,
-    parameters,
-    async execute(params: z.infer<typeof parameters>, ctx) {
+    parameters: Parameters,
+    async execute(params: z.infer<typeof Parameters>, ctx) {
       const skill = await Skill.get(params.name)
 
       if (!skill) {
@@ -103,3 +98,23 @@ export const SkillTool = Tool.define("skill", async (ctx) => {
     },
   }
 })
+
+export const SkillDescription: Tool.DynamicDescription = (agent) =>
+  Effect.gen(function* () {
+    const list = yield* Effect.promise(() => Skill.available(agent))
+    if (list.length === 0) return "No skills are currently available."
+    return [
+      "Load a specialized skill that provides domain-specific instructions and workflows.",
+      "",
+      "When you recognize that a task matches one of the available skills listed below, use this tool to load the full skill instructions.",
+      "",
+      "The skill will inject detailed instructions, workflows, and access to bundled resources (scripts, references, templates) into the conversation context.",
+      "",
+      'Tool output includes a `<skill_content name="...">` block with the loaded content.',
+      "",
+      "The following skills provide specialized sets of instructions for particular tasks",
+      "Invoke this tool to load a skill when a task matches one of the available skills listed below:",
+      "",
+      Skill.fmt(list, { verbose: false }),
+    ].join("\n")
+  })