Clean up namespaces (#410)

No meaningful code changes, just lots of namespace shuffling to have fewer namespaces and to put things in better namespaces.

src/ModelContextProtocol/Protocol/ToolAnnotations.cs

@@ -0,0 +1,96 @@
+using System.Text.Json.Serialization;
+
+namespace ModelContextProtocol.Protocol;
+
+/// <summary>
+/// Represents additional properties describing a <see cref="Tool"/> to clients.
+/// </summary>
+/// <remarks>
+/// All properties in <see cref="ToolAnnotations"/> are hints.
+/// They are not guaranteed to provide a faithful description of tool behavior (including descriptive properties like `title`).
+/// Clients should never make tool use decisions based on <see cref="ToolAnnotations"/> received from untrusted servers.
+/// </remarks>
+public class ToolAnnotations
+{
+    /// <summary>
+    /// Gets or sets a human-readable title for the tool that can be displayed to users.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// The title provides a more descriptive, user-friendly name for the tool than the tool's
+    /// programmatic name. It is intended for display purposes and to help users understand
+    /// the tool's purpose at a glance.
+    /// </para>
+    /// <para>
+    /// Unlike the tool name (which follows programmatic naming conventions), the title can
+    /// include spaces, special characters, and be phrased in a more natural language style.
+    /// </para>
+    /// </remarks>
+    [JsonPropertyName("title")]
+    public string? Title { get; set; }
+
+    /// <summary>
+    /// Gets or sets whether the tool may perform destructive updates to its environment.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// If <see langword="true"/>, the tool may perform destructive updates to its environment.
+    /// If <see langword="false"/>, the tool performs only additive updates.
+    /// This property is most relevant when the tool modifies its environment (ReadOnly = false).
+    /// </para>
+    /// <para>
+    /// The default is <see langword="true"/>.
+    /// </para>
+    /// </remarks>
+    [JsonPropertyName("destructiveHint")]
+    public bool? DestructiveHint { get; set; }
+
+    /// <summary>
+    /// Gets or sets whether calling the tool repeatedly with the same arguments 
+    /// will have no additional effect on its environment.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// This property is most relevant when the tool modifies its environment (ReadOnly = false).
+    /// </para>
+    /// <para>
+    /// The default is <see langword="false"/>.
+    /// </para>
+    /// </remarks>
+    [JsonPropertyName("idempotentHint")]
+    public bool? IdempotentHint { get; set; }
+
+    /// <summary>
+    /// Gets or sets whether this tool may interact with an "open world" of external entities.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// If <see langword="true"/>, the tool may interact with an unpredictable or dynamic set of entities (like web search).
+    /// If <see langword="false"/>, the tool's domain of interaction is closed and well-defined (like memory access).
+    /// </para>
+    /// <para>
+    /// The default is <see langword="true"/>.
+    /// </para>
+    /// </remarks>
+    [JsonPropertyName("openWorldHint")]
+    public bool? OpenWorldHint { get; set; }
+
+    /// <summary>
+    /// Gets or sets whether this tool does not modify its environment.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// If <see langword="true"/>, the tool only performs read operations without changing state.
+    /// If <see langword="false"/>, the tool may make modifications to its environment.
+    /// </para>
+    /// <para>
+    /// Read-only tools do not have side effects beyond computational resource usage.
+    /// They don't create, update, or delete data in any system.
+    /// </para>
+    /// <para>
+    /// The default is <see langword="false"/>.
+    /// </para>
+    /// </remarks>
+    [JsonPropertyName("readOnlyHint")]
+    public bool? ReadOnlyHint { get; set; }
+}