Trait ResourceDefinition

Source

pub trait ResourceDefinition:
    HasResourceMetadata
    + HasResourceDescription
    + HasResourceUri
    + HasResourceMimeType
    + HasResourceSize
    + HasResourceAnnotations
    + HasResourceMeta
    + Send
    + Sync {
    // Provided methods
    fn display_name(&self) -> &str { ... }
    fn to_resource(&self) -> Resource { ... }
}

Expand description

Complete MCP Resource Creation - Build readable resources that clients can access.

This trait represents a complete, working MCP resource that can be registered with a server and accessed by clients. When you implement the required metadata traits, you automatically get ResourceDefinition for free via blanket implementation.

§What This Enables

Resources implementing ResourceDefinition become full MCP citizens that are:

🔍 Discoverable via resources/list requests
📖 Readable via resources/read requests
🎯 Template-capable with URI variable substitution
📡 Protocol-ready for JSON-RPC communication

§Complete Working Example

use std::collections::HashMap;

// This struct will automatically implement ResourceDefinition!
struct ApiDataFeed {
    endpoint: String,
    api_key: String,
}

impl HasResourceMetadata for ApiDataFeed {
    fn name(&self) -> &str { "api_data" }
    fn title(&self) -> Option<&str> { Some("Live API Data Feed") }
}

impl HasResourceDescription for ApiDataFeed {
    fn description(&self) -> Option<&str> {
        Some("Real-time data feed from external API with caching")
    }
}

impl HasResourceUri for ApiDataFeed {
    fn uri(&self) -> &str { "https://api.example.com/data/{dataset}" }
}

impl HasResourceMimeType for ApiDataFeed {
    fn mime_type(&self) -> Option<&str> { Some("application/json") }
}

impl HasResourceSize for ApiDataFeed {
    fn size(&self) -> Option<u64> { None } // Dynamic size
}

// Implement remaining required traits...
impl HasResourceAnnotations for ApiDataFeed { fn annotations(&self) -> Option<&crate::meta::Annotations> { None } }
impl HasResourceMeta for ApiDataFeed { fn resource_meta(&self) -> Option<&HashMap<String, serde_json::Value>> { None } }

// 🎉 ApiDataFeed now automatically implements ResourceDefinition!
// Clients can discover it and read data with URI templates like "api_data?dataset=users"

§Usage Patterns

§Easy: Use Derive Macros

#[derive(McpResource)]
#[resource(name = "logs", uri = "file:///var/log/{service}.log")]
struct LogFiles { service: String }

§Advanced: Manual Implementation (shown above)

Perfect when you need dynamic URIs, custom metadata, or complex content handling.

§Real-World Resource Ideas

File Resources: Config files, logs, documentation, data exports
API Resources: REST endpoints, GraphQL schemas, webhook data
Data Resources: Database views, CSV exports, JSON feeds, report data
System Resources: Process info, system stats, environment configs
Template Resources: Dynamic content with {variable} substitution

§URI Template Power

Resources support powerful URI templating:

Static:   "file:///config.json"              → Single resource
Template: "file:///logs/{service}.log"       → Multiple resources
Complex:  "api://data/{type}/{id}?fmt={fmt}" → Full parameterization