User GuidesProtocol Tester

Using the Protocol Tester

Test MCP, A2A, and REST endpoints directly inside the Agentic Asset Designer platform with the built-in Protocol Tester—no external tools required.

Overview

The Protocol Tester is an in-app, Postman-like component that lets you:

  • Discover capabilities — Connect to an MCP or A2A URL and see tools, resources, prompts, or skills automatically.
  • Run requests — Fill in parameters using schema-based forms (no raw JSON), then view status, headers, and response body.
  • Copy cURL — Generate a cURL command from any request for use in scripts or external tools.
  • Replay history — Recent requests are saved so you can replay or compare results.

Protocol is auto-detected from the URL (e.g. paths containing /mcp or /a2a), and all requests go through the platform’s proxy so CORS and browser security are handled for you.

Where to Find It

Standalone page

  • Open the sidebar and click Protocol Tester (flask icon).
  • You’ll see the full tester with URL bar, optional auth and headers, and a history drawer.
  • Use this when you want to test any MCP, A2A, or REST URL (including servers not yet registered in the platform).

MCP Server detail — Test tab

  • Open an MCP server from the Servers list, then select the Test tab.
  • The tester is pre-filled with that server’s MCP endpoint URL and auth (if configured).
  • Protocol is locked to MCP; after you click Send, tools, resources, and prompts appear as cards you can run.

Agent Card detail — Test tab

  • Open an agent card from the Agent Cards list, then select the Test tab.
  • The tester is pre-filled with the card’s A2A endpoint; discovered skills are shown.
  • Protocol is locked to A2A so you can send messages and test skills.

REST API detail — Playground tab

  • Open a REST API from the REST APIs list, then select the Playground tab.
  • The tester shows all endpoints as interactive cards with method, path, and parameter fields.
  • Click Refresh to reload endpoints from the API definition.
  • Protocol is locked to REST.

Exploratory Testing sessions

  • When an external tester opens an exploratory session entity, the Protocol Tester opens pre-configured for that specific entity (tool, skill, or endpoint).
  • Interactions are automatically captured and stored as session data.

How It Works

  1. Enter or use the pre-filled URL (e.g. https://your-domain.com/api/platform/SERVER_ID/mcp).
  2. Click Send — The tester detects the protocol, calls the appropriate discovery (e.g. initialize, tools/list, resources/list, prompts/list for MCP), and displays the results.
  3. Use the discovery cards — Each tool, resource, or prompt has a Test button. Click it to open a form built from the schema (text, number, select, etc.).
  4. Submit and view the response — Status, timing, and body are shown; you can switch between formatted JSON, raw text, and headers, and copy the request as cURL.

MCP HTTP-Streamable and SSE

Many MCP servers use the HTTP-Streamable transport. The Protocol Tester is built to work with them:

  • Headers — It sends Accept: application/json, text/event-stream and User-Agent: ProtocolTester/1.0 (MCP-HTTP) on every MCP request, so servers that expect these headers will respond correctly.
  • SSE responses — If the server returns Server-Sent Events (e.g. event: message and data: {"result":{...}}), the tester automatically extracts the JSON from the data: line and displays tools and results. No extra configuration is needed.

If discovery finds no tools, resources, or prompts, the UI shows the raw tools/list response (status and body) so you can see exactly what the server returned and debug connection or protocol issues.

Security and Limits

  • Proxy — All outbound requests are sent through the platform’s proxy. Private and internal IPs are blocked (SSRF protection).
  • Auth — Credentials you enter (Bearer token, basic auth, etc.) are used only for the request; they are not stored on the server.
  • Limits — Request body size and timeouts are enforced by the proxy to keep the service stable.

Next Steps

Use the Protocol Tester from the sidebar or from any MCP server or Agent Card Test tab to validate endpoints.

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