modelcontextprotocol/use-mcp
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Glen Maddern 2025-06-02 19:07:59 +10:00
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105
src/react/README.md
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@ -21,17 +21,17 @@ The useMcp hook manages the connection to an MCP server, handles authentication
## Importing
```tsx
import { useMcp } from 'use-mcp';
import { useMcp } from 'use-mcp'
// Optional: Import types if needed
import type { UseMcpOptions, UseMcpResult, Tool } from 'use-mcp';
import type { UseMcpOptions, UseMcpResult, Tool } from 'use-mcp'
```
## Usage
```tsx
import React from 'react';
import { useMcp } from 'use-mcp/react';
import { useChat } from 'ai/react'; // Example integration with Vercel AI SDK
import React from 'react'
import { useMcp } from 'use-mcp/react'
import { useChat } from 'ai/react' // Example integration with Vercel AI SDK
function MyChatComponent() {
const mcp = useMcp({
@ -45,7 +45,7 @@ function MyChatComponent() {
debug: process.env.NODE_ENV === 'development', // Enable debug logs in dev
autoReconnect: true, // Automatically reconnect if connection drops
autoRetry: 5000, // Retry connection every 5s if initial connection fails
});
})
// Example: Using MCP tools with Vercel AI SDK's useChat
const { messages, input, handleInputChange, handleSubmit } = useChat({
@ -55,32 +55,29 @@ function MyChatComponent() {
// Example: Handling tool calls made by the LLM
async onToolCall({ toolCall }) {
if (mcp.state !== 'ready') {
console.error('MCP not ready, cannot handle tool call:', toolCall);
console.error('MCP not ready, cannot handle tool call:', toolCall)
// Return an error or indication that the tool cannot be called
return {
toolCallId: toolCall.toolCallId,
result: { error: 'Tool provider not available' }
};
toolCallId: toolCall.toolCallId,
result: { error: 'Tool provider not available' },
}
}
try {
console.log('Handling tool call via MCP:', toolCall);
const result = await mcp.callTool(
toolCall.toolName,
toolCall.args,
);
console.log('Handling tool call via MCP:', toolCall)
const result = await mcp.callTool(toolCall.toolName, toolCall.args)
return {
toolCallId: toolCall.toolCallId,
result,
};
}
} catch (error) {
console.error('Error calling MCP tool:', error);
console.error('Error calling MCP tool:', error)
return {
toolCallId: toolCall.toolCallId,
result: { error: error instanceof Error ? error.message : String(error) }
};
toolCallId: toolCall.toolCallId,
result: { error: error instanceof Error ? error.message : String(error) },
}
}
},
});
})
return (
<div>
@ -99,8 +96,8 @@ function MyChatComponent() {
<button onClick={() => mcp.authenticate()}>Retry Auth</button>
</p>
)}
{/* Show retry button for general failures */}
{!mcp.authUrl && <button onClick={mcp.retry}>Retry Connection</button>}
{/* Show retry button for general failures */}
{!mcp.authUrl && <button onClick={mcp.retry}>Retry Connection</button>}
</div>
)}
{mcp.state === 'authenticating' && <p>Waiting for authentication...</p>}
@ -124,50 +121,58 @@ function MyChatComponent() {
// Disable input if MCP is not ready and tools might be needed
disabled={mcp.state !== 'ready' && mcp.state !== 'loading'}
/>
<button type="submit" disabled={mcp.state !== 'ready'}>Send</button>
<button type="submit" disabled={mcp.state !== 'ready'}>
Send
</button>
</form>
{/* Optional: Display logs for debugging */}
{mcp.debug && (
<pre style={{ maxHeight: '200px', overflowY: 'auto', fontSize: '0.8em', background: '#eee', padding: '5px' }}>
{mcp.log.map((l, i) => <div key={i}>[{l.level}] {new Date(l.timestamp).toLocaleTimeString()}: {l.message}</div>)}
{mcp.log.map((l, i) => (
<div key={i}>
[{l.level}] {new Date(l.timestamp).toLocaleTimeString()}: {l.message}
</div>
))}
</pre>
)}
{/* Button to clear stored auth data */}
<button onClick={mcp.clearStorage} style={{marginTop: '10px'}}>Clear Stored Auth</button>
{/* Button to clear stored auth data */}
<button onClick={mcp.clearStorage} style={{ marginTop: '10px' }}>
Clear Stored Auth
</button>
</div>
);
)
}
export default MyChatComponent;
export default MyChatComponent
```
### Hook Options (UseMcpOptions)
* url (required): The /sse URL of your MCP server.
* clientName: Name used for OAuth dynamic client registration (if applicable). Defaults to "MCP React Client".
* clientUri: Client URI used for OAuth registration. Defaults to window.location.origin.
* callbackUrl: The absolute URL of your OAuth callback page. Must match the redirect URI registered with your OAuth server and the route where you call onMcpAuthorization. Defaults to /oauth/callback on the current origin.
* storageKeyPrefix: Prefix for keys used in localStorage (e.g., tokens, client info). Defaults to "mcp:auth". Useful to avoid conflicts if multiple MCP instances/apps run on the same origin.
* clientConfig: Information about the client application sent during the MCP handshake. Includes name (default: "mcp-react-client") and version (default: "0.1.0").
* debug: Enable verbose logging to the console and the log state array. Defaults to false.
* autoRetry: If true or a number (milliseconds), automatically tries to reconnect if the initial connection fails. Defaults to false. Uses a 5000ms delay if set to true.
* autoReconnect: If true or a number (milliseconds), automatically tries to reconnect if an established connection is lost. Defaults to 3000 (3 seconds). Set to false to disable.
* popupFeatures: The features string passed to window.open for the OAuth popup. Defaults to "width=600,height=700,resizable=yes,scrollbars=yes,status=yes".
- url (required): The /sse URL of your MCP server.
- clientName: Name used for OAuth dynamic client registration (if applicable). Defaults to "MCP React Client".
- clientUri: Client URI used for OAuth registration. Defaults to window.location.origin.
- callbackUrl: The absolute URL of your OAuth callback page. Must match the redirect URI registered with your OAuth server and the route where you call onMcpAuthorization. Defaults to /oauth/callback on the current origin.
- storageKeyPrefix: Prefix for keys used in localStorage (e.g., tokens, client info). Defaults to "mcp:auth". Useful to avoid conflicts if multiple MCP instances/apps run on the same origin.
- clientConfig: Information about the client application sent during the MCP handshake. Includes name (default: "mcp-react-client") and version (default: "0.1.0").
- debug: Enable verbose logging to the console and the log state array. Defaults to false.
- autoRetry: If true or a number (milliseconds), automatically tries to reconnect if the initial connection fails. Defaults to false. Uses a 5000ms delay if set to true.
- autoReconnect: If true or a number (milliseconds), automatically tries to reconnect if an established connection is lost. Defaults to 3000 (3 seconds). Set to false to disable.
- popupFeatures: The features string passed to window.open for the OAuth popup. Defaults to "width=600,height=700,resizable=yes,scrollbars=yes,status=yes".
### Hook Return Value (UseMcpResult)
* tools: An array of Tool objects provided by the server. Empty until state is 'ready'.
* state: The current connection state ('discovering', 'authenticating', 'connecting', 'loading', 'ready', 'failed'). Use this to conditionally render UI or enable/disable features.
* error: An error message if state is 'failed'.
* authUrl: If authentication is required and the popup was potentially blocked, this URL string can be used to let the user manually open the auth page (e.g., <a href={authUrl} target="_blank">...</a>).
* log: An array of log messages { level, message, timestamp }. Useful for debugging when debug option is true.
* callTool(name, args): An async function to execute a tool on the MCP server. Throws an error if the client isn't ready or the call fails.
* retry(): Manually triggers a reconnection attempt if the state is 'failed'.
* disconnect(): Disconnects the client from the server.
* authenticate(): Manually attempts to start the authentication flow. Useful for triggering the popup via a user click if it was initially blocked.
* clearStorage(): Removes all authentication-related data (tokens, client info, code verifier, state) for the configured server URL from localStorage. Useful for development or allowing users to "log out". Automatically disconnects the client.
- tools: An array of Tool objects provided by the server. Empty until state is 'ready'.
- state: The current connection state ('discovering', 'authenticating', 'connecting', 'loading', 'ready', 'failed'). Use this to conditionally render UI or enable/disable features.
- error: An error message if state is 'failed'.
- authUrl: If authentication is required and the popup was potentially blocked, this URL string can be used to let the user manually open the auth page (e.g., <a href={authUrl} target="_blank">...</a>).
- log: An array of log messages { level, message, timestamp }. Useful for debugging when debug option is true.
- callTool(name, args): An async function to execute a tool on the MCP server. Throws an error if the client isn't ready or the call fails.
- retry(): Manually triggers a reconnection attempt if the state is 'failed'.
- disconnect(): Disconnects the client from the server.
- authenticate(): Manually attempts to start the authentication flow. Useful for triggering the popup via a user click if it was initially blocked.
- clearStorage(): Removes all authentication-related data (tokens, client info, code verifier, state) for the configured server URL from localStorage. Useful for development or allowing users to "log out". Automatically disconnects the client.
### Setting up the OAuth Callback Route
Remember to create the callback route (e.g., /oauth/callback) specified in callbackUrl and have it execute the onMcpAuthorization function exported from the main use-mcp package. See the root README for an example.
Remember to create the callback route (e.g., /oauth/callback) specified in callbackUrl and have it execute the onMcpAuthorization function exported from the main use-mcp package. See the root README for an example.

6
src/react/index.ts
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@ -3,8 +3,8 @@
* Provides the useMcp hook and related types.
*/
export { useMcp } from './useMcp.js';
export type { UseMcpOptions, UseMcpResult } from './types.js';
export { useMcp } from './useMcp.js'
export type { UseMcpOptions, UseMcpResult } from './types.js'
// Re-export core Tool type for convenience when using hook result?
export type { Tool } from '@modelcontextprotocol/sdk/types.js';
export type { Tool } from '@modelcontextprotocol/sdk/types.js'

52
src/react/types.ts
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@ -1,36 +1,36 @@
import { Tool } from '@modelcontextprotocol/sdk/types.js';
import { Tool } from '@modelcontextprotocol/sdk/types.js'
export type UseMcpOptions = {
/** The /sse URL of your remote MCP server */
url: string;
url: string
/** OAuth client name for registration (if dynamic registration is used) */
clientName?: string;
clientName?: string
/** OAuth client URI for registration (if dynamic registration is used) */
clientUri?: string;
clientUri?: string
/** Custom callback URL for OAuth redirect (defaults to /oauth/callback on the current origin) */
callbackUrl?: string;
callbackUrl?: string
/** Storage key prefix for OAuth data in localStorage (defaults to "mcp:auth") */
storageKeyPrefix?: string;
storageKeyPrefix?: string
/** Custom configuration for the MCP client identity */
clientConfig?: {
name?: string;
version?: string;
};
name?: string
version?: string
}
/** Custom headers that can be used to bypass auth */
customHeaders?: Record<string, string>;
customHeaders?: Record<string, string>
/** Whether to enable verbose debug logging to the console and the log state */
debug?: boolean;
debug?: boolean
/** Auto retry connection if initial connection fails, with delay in ms (default: false) */
autoRetry?: boolean | number;
autoRetry?: boolean | number
/** Auto reconnect if an established connection is lost, with delay in ms (default: 3000) */
autoReconnect?: boolean | number;
autoReconnect?: boolean | number
/** Popup window features string (dimensions and behavior) for OAuth */
popupFeatures?: string;
};
popupFeatures?: string
}
export type UseMcpResult = {
/** List of tools available from the connected MCP server */
tools: Tool[];
tools: Tool[]
/**
* The current state of the MCP connection:
* - 'discovering': Checking server existence and capabilities (including auth requirements).
@ -40,16 +40,16 @@ export type UseMcpResult = {
* - 'ready': Connected and ready for tool calls.
* - 'failed': Connection or authentication failed. Check the `error` property.
*/
state: 'discovering' | 'authenticating' | 'connecting' | 'loading' | 'ready' | 'failed';
state: 'discovering' | 'authenticating' | 'connecting' | 'loading' | 'ready' | 'failed'
/** If the state is 'failed', this provides the error message */
error?: string;
error?: string
/**
* If authentication requires user interaction (e.g., popup was blocked),
* this URL can be presented to the user to complete authentication manually in a new tab.
*/
authUrl?: string;
authUrl?: string
/** Array of internal log messages (useful for debugging) */
log: { level: 'debug' | 'info' | 'warn' | 'error'; message: string; timestamp: number }[];
log: { level: 'debug' | 'info' | 'warn' | 'error'; message: string; timestamp: number }[]
/**
* Function to call a tool on the MCP server.
* @param name The name of the tool to call.
@ -57,18 +57,18 @@ export type UseMcpResult = {
* @returns A promise that resolves with the tool's result.
* @throws If the client is not in the 'ready' state or the call fails.
*/
callTool: (name: string, args?: Record<string, unknown>) => Promise<any>;
callTool: (name: string, args?: Record<string, unknown>) => Promise<any>
/** Manually attempts to reconnect if the state is 'failed'. */
retry: () => void;
retry: () => void
/** Disconnects the client from the MCP server. */
disconnect: () => void;
disconnect: () => void
/**
* Manually triggers the authentication process. Useful if the initial attempt failed
* due to a blocked popup, allowing the user to initiate it via a button click.
* @returns A promise that resolves with the authorization URL opened (or intended to be opened),
* or undefined if auth cannot be started.
*/
authenticate: () => void;
authenticate: () => void
/** Clears all stored authentication data (tokens, client info, etc.) for this server URL from localStorage. */
clearStorage: () => void;
};
clearStorage: () => void
}