Invoking Tools
Test MCP tools interactively using the form UI or raw JSON input.
Invoking Tools
Opening the test dialog
Click Test on any tool card. A dialog opens with two modes:
- Form — auto-generated input form based on the tool's JSON Schema
- Raw JSON — a textarea for crafting the
argumentsobject manually
Form mode
MCPHub generates a form from the tool's inputSchema. Supported field types:
| Schema type | Input rendered |
|---|---|
string | Text input |
number / integer | Number input |
boolean | Toggle switch |
string with enum | Dropdown select |
| Complex nested types | Falls back to JSON textarea |
Fill in the fields and click Run.
Raw JSON mode
Toggle to Raw JSON to write the arguments object directly:
This is useful for tools with complex nested schemas, arrays, or types that don't map to simple form fields.
Results
After running a tool, the result panel shows:
- Status — success or error (with error message)
- Duration — wall-clock time for the tool call (ms)
- Response — the full JSON response from the server, syntax-highlighted
- Audit log link — a link to the specific tool call record in the audit log
Audit trail
Every invocation from the playground is logged in the tool call audit log with:
caller_agent = "mcphub-playground"- The actual tool name, server, and response details
- Duration and output size
This means playground tests are visible in analytics and can trigger alert rules.