fix(tools/looker): address feedback for agent tool (#2834)

## Description

Addresses the feedback from the maintainers regarding the `looker-agent`
tool.

Author: hiracky16

docs/en/resources/tools/looker/looker-agent.md

@@ -26,7 +26,18 @@ name: agent_manage
 type: looker-agent
 source: my_looker_source
 description: |
-  Manage Looker AI Agents.
+  Manage Looker AI Agents. This tool allows you to perform various operations on Looker Agents, 
+  including listing all available agents, retrieving details for a specific agent, 
+  creating a new agent, and deleting an existing one.
+
+  Parameters:
+  - operation (required): The action to perform.
+    - 'list': Returns a list of all existing agents. No other parameters needed.
+    - 'get': Retrieves detailed information about a specific agent. Requires 'agent_id'.
+    - 'create': Creates a new Looker AI Agent. Requires 'name'.
+    - 'delete': Removes an existing agent. Requires 'agent_id'.
+  - agent_id (optional): The unique identifier of the agent. Required for 'get' and 'delete' operations.
+  - name (optional): The display name for the new agent. Required for 'create' operation.
 ```
 
 ## Parameters
@@ -76,11 +87,3 @@ Delete an agent by its ID.
 
 ## Dependencies
 This tool requires the underlying Looker Go SDK to support the `Agent` API resource (v0.26.6+).
-
-## Reference
-
-| **field**   | **type** | **required** | **description**                                    |
-|-------------|:--------:|:------------:|----------------------------------------------------|
-| type        |  string  |     true     | Must be "looker-agent".             |
-| source      |  string  |     true     | Name of the source the SQL should execute on.      |
-| description |  string  |     true     | Description of the tool that is passed to the LLM. |

internal/tools/looker/lookeragent/lookeragent_test.go

@@ -38,14 +38,14 @@ func TestParseFromYamlLookerAgent(t *testing.T) {
 			desc: "basic example",
 			in: `
             kind: tool
-            name: example_tool
+            name: agent_manage
             type: looker-agent
             source: my-instance
             description: some description
                                 `,
 			want: server.ToolConfigs{
-				"example_tool": lkr.Config{
-					Name:         "example_tool",
+				"agent_manage": lkr.Config{
+					Name:         "agent_manage",
 					Type:         "looker-agent",
 					Source:       "my-instance",
 					Description:  "some description",