Class Tool

Namespace

ModelContextProtocol.Protocol

Assembly

ModelContextProtocol.Core.dll

Represents a tool that the server is capable of calling.

public sealed class Tool : IBaseMetadata

Inheritance

object

Tool

Implements

IBaseMetadata

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Properties

Annotations

Gets or sets optional additional tool information and behavior hints.

[JsonPropertyName("annotations")]
public ToolAnnotations? Annotations { get; set; }

Property Value

ToolAnnotations

Remarks

These annotations provide metadata about the tool's behavior, such as whether it's read-only, destructive, idempotent, or operates in an open world. They also can include a human-readable title. Note that these are hints and should not be relied upon for security decisions.

Description

Gets or sets a human-readable description of the tool.

[JsonPropertyName("description")]
public string? Description { get; set; }

Property Value

string

Remarks

This description helps the AI model understand what the tool does and when to use it. It should be clear, concise, and accurately describe the tool's purpose and functionality.

The description is typically presented to AI models to help them determine when and how to use the tool based on user requests.

InputSchema

Gets or sets a JSON Schema object defining the expected parameters for the tool.

[JsonPropertyName("inputSchema")]
public JsonElement InputSchema { get; set; }

Property Value

JsonElement

Remarks

The schema must be a valid JSON Schema object with the "type" property set to "object". This is enforced by validation in the setter which will throw an ArgumentException if an invalid schema is provided.

The schema typically defines the properties (parameters) that the tool accepts, their types, and which ones are required. This helps AI models understand how to structure their calls to the tool.

If not explicitly set, a default minimal schema of {"type":"object"} is used.

Meta

Gets or sets metadata reserved by MCP for protocol-level metadata.

[JsonPropertyName("_meta")]
public JsonObject? Meta { get; set; }

Property Value

JsonObject

Remarks

Implementations must not make assumptions about its contents.

Name

Gets or sets the unique identifier for this item.

[JsonPropertyName("name")]
public string Name { get; set; }

Property Value

string

OutputSchema

Gets or sets a JSON Schema object defining the expected structured outputs for the tool.

[JsonPropertyName("outputSchema")]
public JsonElement? OutputSchema { get; set; }

Property Value

JsonElement?

Remarks

The schema must be a valid JSON Schema object with the "type" property set to "object". This is enforced by validation in the setter which will throw an ArgumentException if an invalid schema is provided.

The schema should describe the shape of the data as returned in StructuredContent.

Title

Gets or sets a title.

[JsonPropertyName("title")]
public string? Title { get; set; }

Property Value

string

Remarks

This is intended for UI and end-user contexts. It is optimized to be human-readable and easily understood, even by those unfamiliar with domain-specific terminology. If not provided, Name may be used for display (except for tools, where Title, if present, should be given precedence over using Name).