MCP Playground adds schema linter, public API
MCP Playground is an open-source, browser-based tool for inspecting and running remote MCP servers, and this update turns it into a more serious ops and quality layer. The new Schema Linter grades servers A–F using 15+ checks across tool descriptions, JSON Schema completeness, naming, duplicates, and metadata, while also estimating token cost per tool. The release also adds a CORS-enabled public REST API for health checks, inspection, and registry queries, plus support for ws:// and wss:// transports alongside HTTP and SSE.
This feels like a meaningful upgrade from “handy playground” to “real MCP infrastructure.” The strongest move here is the linter, because it attacks the ecosystem’s biggest hidden problem: lots of servers are technically connectable but still unpleasant or expensive for models to use.
- –The A-F grading system makes MCP schema quality legible at a glance, which is great for server authors and reviewers.
- –Token-cost estimates are a smart addition because tool count alone does not tell you how expensive a server is to expose to an agent.
- –The public API makes the product useful in CI, monitoring, and registry automation, not just manual testing.
- –WebSocket support broadens compatibility and removes a practical friction point for newer MCP transports.
- –The main risk is that a quality score can be over-trusted if teams treat it like a full proxy for usability or task fit.
DISCOVERED
67d ago
2026-03-21
PUBLISHED
67d ago
2026-03-20
RELEVANCE
AUTHOR
samsec_io