Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/devolutions/avalonia-extensions/avalonia-devtools-mcpnpx skills add Devolutions/avalonia-extensions --skill avalonia-devtools-mcpgit clone --depth 1 https://github.com/Devolutions/avalonia-extensionsWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00044 | $0.00665 |
| Opus 5 | $0.00022 | $0.00332 |
| Sonnet 5 | $0.00009 | $0.00133 |
| Haiku 4.5 | $0.00004 | $0.00067 |
Grade A, and why
avalonia-devtools-mcp scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 64 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Avalonia DevTools MCP
Use this skill when the task involves validating or debugging runtime UI behavior in a running Avalonia app, especially when visual inspection, tree traversal, property/style inspection, or screenshots are needed.
When to use
- "Show me the visual tree"
- "Find this control in the running app"
- "What styles/properties are applied at runtime?"
- "Take a screenshot of this panel/window"
- "Simulate click/text input and verify result"
Preconditions
- DevTools MCP server configured in user MCP config (for VS Code in this environment):
~/Library/Application Support/Code/User/mcp.json
- Tool installed:
dotnet tool install --global AvaloniaUI.DeveloperTools
- App instrumentation in target app:
AvaloniaUI.DiagnosticsSupportpackage.WithDeveloperTools()orthis.AttachDeveloperTools()at startup- Keep this instrumentation development-only (Debug), since MCP enables live inspection, mutation, and input simulation.
Standard workflow
attach-to-appwith noid- If multiple/any clients returned, select one and call
attach-to-appwith thatid - Inspect with:
tree(roots/subtree)search(type/x:Name)props,styles,resourcesscreenshot
- Interact with:
input,action,set-prop,pseudo-class
detachwhen done
Important pitfalls
- Do not tell users to press F12 for MCP connectivity. F12 opens standalone tools and does not establish MCP attach by itself.
attach-to-appcommonly returns an app list first; a second call with selectedidis expected.- Node IDs are ephemeral; reacquire via
tree/searchafter UI changes.
License/auth caveat observed in this repo
In this environment, forcing AVALONIA_TOOLS_LICENSE_KEY through MCP server env could produce:
Authenticated session does not have access to required product: avalonia-developer-tools-console
Working behavior was restored by removing explicit MCP env override and relying on an already-authenticated DevTools session.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 3d ago First seen · 64 lines · 44 tokens per session scan A 13d4341a63d0
avalonia-devtools-mcp is a skill published in the GitHub repository Devolutions/avalonia-extensions (79 stars, last pushed 5d ago), licensed MIT. It adds 44 tokens to every session and 665 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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chat-perf
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cpu-profile-analysis
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