Add agent library

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/agent/tool.go

@@ -0,0 +1,84 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package agent
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"go.probo.inc/probo/pkg/llm"
+)
+
+type (
+	ToolResult struct {
+		Content string
+		IsError bool
+	}
+
+	ToolDescriptor interface {
+		Name() string
+		Definition() llm.Tool
+	}
+
+	Tool interface {
+		ToolDescriptor
+		Execute(ctx context.Context, arguments string) (ToolResult, error)
+	}
+
+	functionTool[P any] struct {
+		name        string
+		description string
+		fn          func(ctx context.Context, params P) (ToolResult, error)
+		schema      json.RawMessage
+	}
+)
+
+func FunctionTool[P any](
+	name string,
+	description string,
+	fn func(ctx context.Context, params P) (ToolResult, error),
+) Tool {
+	schema := jsonSchemaFor[P]()
+
+	return &functionTool[P]{
+		name:        name,
+		description: description,
+		fn:          fn,
+		schema:      schema,
+	}
+}
+
+func (t *functionTool[P]) Name() string { return t.name }
+
+func (t *functionTool[P]) Definition() llm.Tool {
+	return llm.Tool{
+		Name:        t.name,
+		Description: t.description,
+		Parameters:  t.schema,
+	}
+}
+
+func (t *functionTool[P]) Execute(ctx context.Context, arguments string) (ToolResult, error) {
+	var params P
+	if err := json.Unmarshal([]byte(arguments), &params); err != nil {
+		return ToolResult{
+			Content: fmt.Sprintf("Invalid parameters: %s", err.Error()),
+			IsError: true,
+		}, nil
+	}
+
+	return t.fn(ctx, params)
+}