Free, private browser tools for MCP developers
Convert, validate,
and debug MCP.
Convert Claude Desktop MCP JSON to Codex TOML, validate Registry server.json files, trace OAuth 401 metadata, and inspect MCP Apps, Tasks, security, and agent configuration. Fourteen focused browser tools—free, local-first, and usable without an account.
Browse by workflow
Start with the problem.
Each collection explains the workflow and links to the right focused tools, so both people and search crawlers can discover related pages.
Free MCP tools
Convert client configs, validate Tasks and Apps, scan security, debug OAuth, and publish Registry metadata.
Explore MCP tools → 02 · Most used workflowClaude JSON to Codex TOML
See the exact field mapping, conversion example, secret-handling rules, and startup troubleshooting steps.
Follow the config guide → 02 · 12 toolsAI agent tools
Validate MCP 2026, Tasks, Apps, AG-UI, A2UI, AGENTS.md and SKILL.md, then publish discovery resources.
Explore agent tools → Maintained · 8 downloadsDeveloper agent skills
Download a deliberately small set of reviewable engineering skills with explicit inputs, guardrails, outputs, and plain-text source.
Browse maintained skills →MCP field notes
Start with the failure you can see.
Short, reproducible walkthroughs built around the config, response, or deployment symptom in front of you. Each one ends in a browser tool you can use on your own data.
Remove the handshake without breaking older clients
A two-path migration from initialize and session IDs to MCP 2026 stateless requests.
Move a working Claude MCP server into Codex
Translate the JSON, keep environment variables intact, then scan the TOML before saving it.
Convert a real config → Authentication · 7 minTrace a remote MCP server that only returns 401
Check protected-resource metadata, issuer linkage, scopes and PKCE in the order the client sees them.
Debug the metadata chain → MCP Apps · 7 minFix an MCP App that opens as a blank panel
Follow the tool result to its ui:// resource, MIME type, CSP and visibility metadata.
Find why an MCP Task never leaves “working”
Capture successive snapshots and look for timestamp regressions, missing results and terminal-state mistakes.
Read the task trace → Distribution · 8 minPrepare server.json before the Registry rejects it
Check package identity, transport fields, version alignment and the document size before publishing.
Prepare the listing → Lab note · 6 fixturesTest the converter against field-preservation cases
Copy stdio, remote, header, quoted-name and invalid-transport fixtures and compare the expected Codex TOML.
Inspect the conversion cases → Lab note · OAuth chainBreak one edge in an MCP OAuth 401 fixture
Follow challenge discovery, protected-resource metadata, issuer linkage, scopes and token audience.
Run the metadata fixture →Tool directory
Pick one. Use it now.
PrintSpec Lab
Check image pixels, DPI, print dimensions, and PDF page specifications.
Local processing · No uploadMCP Config Lab
Convert between MCP JSON, Codex TOML, and other client configuration formats.
Instant conversion · Local onlyMCP Config Guard
Scan MCP configurations for secrets, risky commands, packages, and scope issues.
Static scan · Nothing storedMCP OAuth Lab
Validate MCP OAuth metadata chains, RFC 9728 linkage, and PKCE S256.
Compatibility score · DiagnosticsAgentFile Check
Check AGENTS.md scope, commands, verification steps, and instruction conflicts.
Quality score · Actionable fixesAgent Skill Guard
Scan SKILL.md structure, permissions, instruction overrides, and supply-chain risks.
Structure score · Safety scoreRegistryReady
Validate and generate server.json metadata for the official MCP Registry.
2025-12-11 schema · 4 KB checkCrawlerPolicy
Analyze AI crawler access and generate Content-Signal policies for search, answers, and training.
Access matrix · Policy builderARD Catalog Lab
Validate and generate ai-catalog.json manifests for Agentic Resource Discovery.
URN checks · Discovery readinessA2UI Stream Lab
Validate A2UI v0.9 JSONL streams, surface lifecycle, component graphs, and data paths.
Local validation · Stream semanticsAG-UI Event Lab
Parse AG-UI SSE and validate event fields, message and tool-call lifecycles, run IDs, and JSON Patch.
Local validation · SSE timelineMCP App Ready
Validate MCP Apps tool links, ui:// resources, HTML content, visibility, permissions, and sandbox CSP.
2026-01-26 stable · Local onlyMCP Task Trace
Validate asynchronous MCP task states, payloads, timestamps, polling, terminal transitions, and 2025 migration.
Lifecycle trace · JSONLMCP 2026 Stateless Check
Validate server/discover, per-request metadata, HTTP headers, JSON-RPC envelopes, and legacy session migration.
2026-07-28 · Local trace checkNo matching tool found. Try another keyword.
Common questions
About these free tools
Are Guagua Tools free?
Yes. Every listed tool can be opened and used without creating an account or starting a trial.
Do the tools upload my configuration or files?
Most checks and conversions run locally in the browser. Each tool states its processing and privacy boundaries on its own page.
Which MCP clients are supported?
MCP Config Lab covers common formats used by Claude Desktop, Codex, Cursor, VS Code, and Gemini, while the other MCP tools focus on security, OAuth, and Registry metadata.
Can I use these tools on mobile?
Yes. The directory and individual utilities are responsive, although large configuration files are generally easier to review on a desktop screen.
Why Guagua Tools
Small tools.
Clear principles.
- 01
Open and use
No account, no long onboarding, and no unnecessary friction for a simple task.
- 02
Privacy first
If processing can happen in your browser, your configuration and files stay there.
- 03
Explain the result
Get more than a score: see what was found, why it matters, and what to do next.
BOOKMARK THE USEFUL THINGS.
More tools are coming.
Keep this door open.
Browse all tools ↑PURPOSE & METHODOLOGY
A focused tool, with the context to use it well
Guagua Tools was created to publish a curated collection of free MCP, AI agent, and web-development utilities. It is intended for developers and technical creators who need small, focused browser utilities. The tool is free, requires no account, and is paired with original explanations so you can understand the result rather than copy an unexplained output.
How to use the result
Start with a sample or a non-sensitive copy of your data, run the check, and review every finding before changing a production project. Tools are selected for a specific, documented problem. The directory includes original descriptions, topical collections, and direct links to the source repositories so readers can evaluate each utility. Specifications and software evolve, so confirm high-impact decisions against the linked primary documentation.
Privacy and limitations
text or files submitted to individual tools is processed in your browser wherever the tool page states that local processing is used. Avoid entering passwords, access tokens, personal data, or confidential material. Automated output may be incomplete because it cannot know your entire deployment, threat model, or organizational policy.
Independent and transparent
This is an independent developer resource, not an official certification service. Source code and issue tracking are available on GitHub. Read more about the project, review the privacy policy, or report an error.