Real MCP Playground

The Real MCP Playground lets you connect to any live Streamable HTTP MCP server, browse its capabilities, and invoke them directly — no JSON-RPC required.

Connecting to an MCP Server

1. Open Explorer → Connect endpoint.
2. Enter the Streamable HTTP endpoint URL (for example, https://mcp.example.com/mcp).
3. Leave Auto detect selected, or choose MCP server, then click Check connection.
4. Review the initialize results, name and ownership. Click Connect and open Test to save.

If authentication blocks detection, select MCP explicitly and connect without verification, then configure credentials. Connection checks only initialize the server; capability discovery and invocation happen in Test.

The server's tools, resources, and prompts are displayed in the Test tab.

Test Tab

The Test view groups tools, resources, prompts, and other server capabilities into sections. Unsupported server capabilities retain explanatory pages. Client features that Explorer does not yet implement (sampling, elicitation, and roots) sit under the collapsed Additional capabilities disclosure.

Server Info

Shows the server's identity from the initialize response: name, version, protocol version, advertised capability flags, and any instructions text. Click Refresh from server to re-fetch. Collapsed JSON blocks below let you inspect the raw initialize response and the full capability cache.

Tools

Each tool renders as an expandable row showing its description and input schema. Click a row to open an auto-generated form. Fill example inputs fills empty fields using schema defaults, examples, enum values or basic required placeholders while preserving your edits. Review every value before clicking Run tool: complex constraints, schema references and composition may need manual input. Filling examples does not invoke the tool. Tool drafts are kept when switching capability sections. The JSON-RPC response is displayed inline.

Resources

Each resource lists its name, URI, and MIME type. Expand to edit the URI (useful for templated URIs) and click Read resource.

Prompts

Each prompt shows its arguments. Expand to fill in values and click Get prompt to render the message list.

Ping

A simple round-trip latency test. Click Send ping to issue a JSON-RPC ping and record the result; the latest 10 pings are shown in a ring buffer.

Authentication

MCP servers that require authentication return a 401 response. Agent Explorer handles the MCP OAuth 2.1 flow automatically:

1. Parses the WWW-Authenticate header for the resource_metadata URL
2. Fetches the RFC 9728 Protected Resource Metadata document
3. Discovers the Authorization Server from the PRM's authorization_servers field
4. Verifies S256 PKCE support in the AS metadata
5. Initiates OAuth 2.1 Authorization Code + PKCE with the resource parameter (RFC 8707)
6. Stores encrypted access and refresh tokens (AES-256-GCM)
7. Attaches Authorization: Bearer <token> to every subsequent request

If the server doesn't advertise RFC 9728 metadata, configure OAuth manually in the Configure tab.

Configure Tab

The raw capability manifest (tools, resources, prompts) — previously a separate Schema tab — is now available inside the Server Info section of Test, with Expand / Collapse / Copy controls.

Activity and exports

Activity shows the latest 50 invocations saved in this browser. It is local history, not a shared audit log. Export tests previews and downloads Postman collections or curl scripts.

Workspaces

Add an MCP server to a Workspace to group it with related A2A agents. Workspace membership is shared with all team members.

API Routes