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MCP Resources

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GenAIScript
GenAIScript
GenAI Blogger
 Peli
Peli
GenAIScript developer
 Matt Podwysocki
Matt Podwysocki
GenAIScript developer
 Volkan Unsal
Volkan Unsal
GenAIScript enthusiast
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MCP Resources

Section titled “MCP Resources”

In a previous post, we announced how every script can be a MCP tool.

To follow up on this idea, we added support for publishing MCP resources as part of the script execution.

Resources are a core primitive in the Model Context Protocol (MCP) that allow servers to expose data and content that can be read by clients and used as context for LLM interactions.

MCP handles discovery and resolution of resources, so once your script publishes a resource, the MCP client (IDE) is made “aware” of it and it can decide to read it.

ResourceHost Methods

Section titled “ResourceHost Methods”

The ResourceHost interface provides several methods for working with MCP resources:

publishResource

Section titled “publishResource”

The publishResource method allows you to publish a resource with a unique identifier and a file/string/buffer. The rest of the MCP resource publishing process is handled by the GenAIScript framework.

const uri = await host.publishResource("unique-id", file);

You can also provide additional options like description and MIME type:

const uri = await host.publishResource("my-data", content, {
  description: "A sample data file",
  mimeType: "application/json"
});

resources

Section titled “resources”

The resources method returns a list of all available resource references that have been published.

const resourceRefs = await host.resources();
for (const ref of resourceRefs) {
  console.log(`Resource: ${ref.name} (${ref.uri})`);
  if (ref.description) console.log(`  Description: ${ref.description}`);
  if (ref.mimeType) console.log(`  Type: ${ref.mimeType}`);
}

resolveResource

Section titled “resolveResource”

The resolveResource method allows you to resolve URLs to retrieve associated files and resources. It supports various protocols including https, file, git, gist, and vscode.

const result = await host.resolveResource("https://raw.githubusercontent.com/user/repo/main/README.md");
if (result) {
  console.log(`Resolved URL: ${result.uri}`);
  for (const file of result.files) {
    console.log(`File: ${file.filename}`);
    // Access file.content for the actual content
  }
}

Supported URL patterns include:

  • HTTPS URLs: Direct file downloads from web servers
  • GitHub blob URLs: Automatically converted to raw content URLs
  • GitHub asset URLs: Resolved through GitHub API
  • Gist URLs: Access to GitHub gists (e.g., https://gist.github.com/user/gistid)
  • Git repositories: Clone and access files (e.g., https://github.com/user/repo.git)
  • VSCode URLs: gistfs extension URLs for accessing gists
// Examples of supported URL patterns
await host.resolveResource("https://github.com/user/repo/blob/main/file.txt");
await host.resolveResource("gist://abc123def456/myfile.js");
await host.resolveResource("https://github.com/user/repo.git/path/to/file");
await host.resolveResource("vscode://vsls-contrib.gistfs/open?gist=123&file=script.js");

System Resource Tools

Section titled “System Resource Tools”

GenAIScript provides built-in tools for working with resources through the system.resources system script. These tools make it easy to list and read resources in your scripts:

resource_list

Section titled “resource_list”

Lists all available resources from the host, returning their URIs and descriptions.

script({
    system: ["system.resources"]
})


$`Use the resource_list tool to see what resources are available, then read one of them.`

resource_read

Section titled “resource_read”

Reads content from a URL using the same resolution logic as host.resolveResource. Supports all the URL patterns mentioned above.

script({
    system: ["system.resources"]
})


$`Use the resource_read tool to read the content from https://raw.githubusercontent.com/microsoft/genaiscript/main/README.md`

The tool automatically handles content formatting, binary detection, and multiple files.

Next steps

Section titled “Next steps”

Are you ready to build your own MCP tools and resources?

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