tools: static string definitions, no runtime JSON construction

Tool definitions are now &'static str (name, description,
parameters_json) instead of runtime-constructed serde_json::Value.
No more json!() macro, no more ToolDef::new() for tool definitions.

The JSON schema strings are written directly as string literals.
When sent to the API, they can be interpolated without
serialization/deserialization.

Multi-tool modules return fixed-size arrays instead of Vecs:
- memory: [Tool; 12], journal: [Tool; 3]
- channels: [Tool; 4]
- control: [Tool; 3]
- web: [Tool; 2]

ToolDef/FunctionDef remain for backward compat (API wire format,
summarize_args) but are no longer used in tool definitions.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

src/agent/tools/glob.rs

@@ -6,11 +6,8 @@
 
 use anyhow::{Context, Result};
 use serde::Deserialize;
-use serde_json::json;
 use std::path::PathBuf;
 
-use super::ToolDef;
-
 #[derive(Deserialize)]
 struct Args {
     pattern: String,
@@ -21,30 +18,12 @@ struct Args {
 fn default_path() -> String { ".".into() }
 
 pub fn tool() -> super::Tool {
-    super::Tool { def: definition(), handler: |_a, v| Box::pin(async move { glob_search(&v) }) }
-}
-
-fn definition() -> ToolDef {
-    ToolDef::new(
-        "glob",
-        "Find files matching a glob pattern. Returns file paths sorted by \
-         modification time (newest first). Use patterns like '**/*.rs', \
-         'src/**/*.ts', or 'Cargo.toml'.",
-        json!({
-            "type": "object",
-            "properties": {
-                "pattern": {
-                    "type": "string",
-                    "description": "Glob pattern to match files (e.g. '**/*.rs')"
-                },
-                "path": {
-                    "type": "string",
-                    "description": "Base directory to search from (default: current directory)"
-                }
-            },
-            "required": ["pattern"]
-        }),
-    )
+    super::Tool {
+        name: "glob",
+        description: "Find files matching a glob pattern. Returns file paths sorted by modification time (newest first).",
+        parameters_json: r#"{"type":"object","properties":{"pattern":{"type":"string","description":"Glob pattern to match files (e.g. '**/*.rs')"},"path":{"type":"string","description":"Directory to search in (default: current directory)"}},"required":["pattern"]}"#,
+        handler: |_a, v| Box::pin(async move { glob_search(&v) }),
+    }
 }
 
 fn glob_search(args: &serde_json::Value) -> Result<String> {