Files
mcp-use__mcp-use/docs/python/client/resources.mdx
2026-01-22 14:05:54 +01:00

245 lines
6.5 KiB
Plaintext

---
title: "Resources"
description: "How to use resources from the client"
icon: "file"
---
Resources in MCP provide structured access to information that AI models need to understand context. They represent data sources that can be retrieved and used by AI applications, such as files, database records, API responses, or any other structured information.
## What are Resources?
Resources are context data sources with:
- **URI-based identification** for consistent addressing
- **Structured access patterns** with defined schemas
- **Multiple content types** (text, JSON, binary data)
- **Dynamic or static content** that can change over time
Common examples include:
- Configuration files and documents
- Database records and query results
- API responses and external data
- Calendar events and schedules
- User preferences and settings
## Types of Resources
### Direct Resources
Static resources with fixed URIs that always return the same type of content.
### Resource Templates
Dynamic resources that accept parameters to generate different content based on input.
## Listing Available Resources
To see what resources are available from a connected MCP server:
<CodeGroup>
```python Python
import asyncio
from mcp_use import MCPClient
async def list_resources():
# Initialize client with server configuration
config = {
"mcpServers": {
# Your server definitions here
}
}
client = MCPClient(config)
# Connect to servers
await client.create_all_sessions()
# Get a session for a specific server
session = client.get_session("my_server")
# List all available resources - always returns fresh data
resources = await session.list_resources()
for resource in resources:
print(f"Resource: {resource.name}")
print(f"URI: {resource.uri}")
print(f"Description: {resource.description}")
print(f"MIME Type: {resource.mimeType}")
print("---")
# Run the example
asyncio.run(list_resources())
```
</CodeGroup>
### Automatic Resource List Update
When servers send `ResourceListChangedNotification`, it signals that the resource list has changed. The `list_resources()` method always fetches fresh data from the server, ensuring you get up-to-date information.
```mermaid
sequenceDiagram
participant Client
participant Server
Note over Server: Server Changes State
Server->>Server: disable(resource)
Server->>Client: ResourceListChangedNotification
Client->>Client: Log notification
Note over Client: User Calls list_resources()
Client->>Server: list_resources()
Server-->>Client: [updated resources]
Client->>Client: Return fresh data
```
**Important:** Always use `await session.list_resources()` instead of the deprecated `session.resources` property to ensure you get fresh data:
<CodeGroup>
```python Python
# ✅ Recommended - always returns fresh data
resources = await session.list_resources()
# ⚠️ Deprecated - may return stale data
# resources = session.resources
```
</CodeGroup>
## Reading Resources
Resources are accessed using the `read_resource` method with their URI:
<CodeGroup>
```python Python
import asyncio
from mcp_use import MCPClient
from pydantic import HttpUrl
async def read_resource_example():
config = {
"mcpServers": {
# Your server definitions here
}
}
client = MCPClient(config)
await client.create_all_sessions()
session = client.get_session("file_server")
# Read a resource by URI
resource_uri = HttpUrl("file:///path/to/config.json")
result = await session.read_resource(resource_uri)
# Handle the result
for content in result.contents:
if content.mimeType == "application/json":
print(f"JSON content: {content.text}")
elif content.mimeType == "text/plain":
print(f"Text content: {content.text}")
else:
print(f"Binary content length: {len(content.blob)}")
asyncio.run(read_resource_example())
```
</CodeGroup>
## Working with Resource Templates
Resource templates allow dynamic content generation based on parameters:
<CodeGroup>
```python Python
import asyncio
from mcp_use import MCPClient
from pydantic import HttpUrl
async def template_resource_example():
config = {
"mcpServers": {
# Your server definitions here
}
}
client = MCPClient(config)
await client.create_all_sessions()
session = client.get_session("database_server")
# Access a parameterized resource
# Template URI might be: "db://users/{user_id}/profile"
resource_uri = HttpUrl("db://users/12345/profile")
result = await session.read_resource(resource_uri)
# Process the user profile data
for content in result.contents:
print(f"User profile: {content.text}")
asyncio.run(template_resource_example())
```
</CodeGroup>
## Resource Content Types
Resources can contain different types of content:
### Text Content
<CodeGroup>
```python Python
# Text-based resources (JSON, XML, plain text)
result = await session.read_resource(HttpUrl("file:///config.json"))
for content in result.contents:
if hasattr(content, 'text'):
print(f"Text content: {content.text}")
print(f"MIME type: {content.mimeType}")
```
</CodeGroup>
### Binary Content
<CodeGroup>
```python Python
# Binary resources (images, files, etc.)
result = await session.read_resource(HttpUrl("file:///image.png"))
for content in result.contents:
if hasattr(content, 'blob'):
print(f"Binary data size: {len(content.blob)} bytes")
# Save or process binary data
with open("downloaded_image.png", "wb") as f:
f.write(content.blob)
```
</CodeGroup>
## Resource Discovery
Find resources matching specific criteria:
<CodeGroup>
```python Python
async def find_resources():
session = client.get_session("my_server")
resources = await session.list_resources()
# Find JSON configuration files
config_resources = [
r for r in resources
if r.mimeType == "application/json"
and "config" in r.name.lower()
]
for resource in config_resources:
print(f"Found config: {resource.name} at {resource.uri}")
```
</CodeGroup>
## Error Handling
Always handle potential errors when reading resources:
<CodeGroup>
```python Python
try:
result = await session.read_resource(HttpUrl("file:///missing.txt"))
for content in result.contents:
print(f"Content: {content.text}")
except Exception as e:
print(f"Failed to read resource: {e}")
```
</CodeGroup>