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Local mock MCP server: write tools in a browser editor, serve them as MCP endpoints instantly.
instant-mcp is a development/testing tool with 12 tools spanning mock database operations, tool lifecycle management, and introspection. Most tools have basic descriptions and schemas, but critical gaps undermine production readiness. Parameter descriptions are sparse or missing entirely (e.g., list-tables 'table' param has no description; write_tool 'groups' param lacks guidance). Many tools lack output schema documentation. Error handling is minimal, no recovery guidance or actionable error messages. Tool naming is inconsistent: verb_noun for some (write_tool, delete_tool) but inconsistent for others (describe_workspace, run_tool). The server is designed for local development, not agent integration, which explains the gaps.
Delete a group (cannot delete default or control groups)
Delete a tool and its directory
Describe the workspace: tools, groups, tables, and their relationships
Delete a mock table
Echo back the given message
Read the call log with optional filtering
List mock tables and their rows from the local SQLite database
Test-run a tool with the given arguments
describe_workspace has no output schema documented. LLMs cannot plan downstream calls or extract structured data without knowing what fields to expect.
Multiple tools lack parameter descriptions: list-tables 'table' param, run_tool 'args' param, get_call_log 'group'/'tool' params. LLMs cannot infer parameter meaning from names alone.
Destructive tools (delete_tool, delete_group, drop_table) lack confirmation or dry-run support. Agents can irreversibly delete without safeguards.
No error handling guidance. Tools return raw errors with no recovery hints. E.g., 'Tool not found' gives no hint to call describe_workspace or list available tools.
| Scored | Grade | Overall | Spec posture | Rubric |
|---|---|---|---|---|
| 2026-09-23 | D | 57 | 2026-07-28+ | v2 |
Insert or replace rows in a mock table
Create or update a group and return its MCP endpoint URL
Create a mock table with the given columns
Create or update a tool with TypeScript code
Tool naming inconsistency: describe_workspace vs write_tool vs run_tool. Some use verb_noun, others use verb_object. Inconsistency increases LLM confusion when many tools are available.