wasm-mcp is answering right now. Last checked 12 min ago. 147 installs a week from npm. It exposes 9 tools. Last commit 29 Oct 2026.
Read-only MCP server for the WebAssembly spec: instructions, types, sections, search, proposals.
Installs per day
peak 31 · avg 12 · +139% w/w
a month agotoday
Uptime history
91 days of history · worst day 95%
91 days agonow
100.0%
Uptime 24h
91 of 91 checks
9
Tools
read from the server
193 ms
Response time
average over 24h
147
Installs / week
npm and PyPI
Nothing serious here today
Today is the operative word: we check wasm-mcp every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.
Connect this server
Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 12 min ago.
run in your terminal
claude mcp add wasm-mcp --transport http https://mcp.xyzzylabs.ai/wasm/mcpSettings → Connectors → Add custom connector, then paste this address
https://mcp.xyzzylabs.ai/wasm/mcp~/.codex/config.toml
[mcp_servers.wasm-mcp]
url = "https://mcp.xyzzylabs.ai/wasm/mcp".cursor/mcp.json
{
"mcpServers": {
"wasm-mcp": {
"url": "https://mcp.xyzzylabs.ai/wasm/mcp"
}
}
}.vscode/mcp.json
{
"servers": {
"wasm-mcp": {
"type": "http",
"url": "https://mcp.xyzzylabs.ai/wasm/mcp"
}
}
}Available tools 9
Read directly from the server with tools/list, grouped by what they act on.
If a tool disappears, we record the date.
instruction
instruction_get
Fetch one WebAssembly instruction by mnemonic (`i32.add`) or binary opcode (`0x6a`, multi-byte `0xfd 0x89 0x02`): opcode bytes, category, introducing version, stack type signature, validation/execution anchors + URLs, and `traps` (runtime trap conditions with canonical names; empty + `can_trap:false` when it never traps).
instruction_list
Enumerate WebAssembly instructions, filterable by `category`, `introduced_in` (1.0|2.0|3.0), mnemonic `prefix`, and `can_trap` (only trapping / only non-trapping). Rows (incl. `can_trap`) sorted by opcode.
instruction_search
Ranked free-text search across instruction mnemonics, categories, and opcode hex. Returns hits with a `matched_on` field.
section
section_get
Fetch one spec clause by id or anchor across `core` / `js-api` / `web-api` (`syntax-numtype`, `valid-unreachable`, `modules`, `streaming-modules`, …): title, prose, cross-references, SpecTec formal refs, and rendered URL.
section_list
Navigate the clause tree of a spec (`core` / `js-api` / `web-api`), filterable by source `path` (`syntax`, `valid`, `exec`, `binary`, `text`, `appendix`), `anchor_prefix`, `titled_only`, and `max_level`.
spec
spec_search
Full-text search across clause anchors, titles, and prose of a spec (`core` / `js-api` / `web-api`). Ranked anchor-exact > title > anchor > prose, with snippets for body matches.
spec_version
Return this server's package version plus the pinned upstream commit SHA(s) the bundled data was indexed from.
proposal
proposal_list
List WebAssembly proposals + phases. Filter by `status` (phase-0…phase-5, finished, inactive), `phase` (0–5), `champion`, `affects` (core|js-api|web-api), or `contains`.
type
type_get
Look up a value type (`i32`, `funcref`, `v128`, …) or type form (`functype`, `limits`, `memtype`, …): classification, sibling members, defining clause prose, formal refs, and URL.
Endpoints
| URL | Transport | State | Latency | Checked |
|---|---|---|---|---|
| https://mcp.xyzzylabs.ai/wasm/mcp | streamable-http | answering | 139 ms | 12 min ago |
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wasm-mcp — questions
Answers built from our own checks of this server.
What can wasm-mcp do?
It exposes 9 tools, read directly from the server on our last check. Among them: instruction_get, instruction_list, instruction_search, proposal_list, section_get, section_list and 3 more. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README.
How MCP servers expose tools in the first place →
What is wasm-mcp mostly used for?
Its tools cluster around instruction, section and spec. That is what this server is built to work with — the grouping comes from the actual tool names, not from a category we assigned.
Is wasm-mcp working right now?
We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 193 ms. The bar chart above shows every period we have measured.
How do I connect wasm-mcp?
Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.
Does wasm-mcp need an API key?
No. wasm-mcp completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 9 of them are readable on this page. This is what we observed, not what the docs claim.
How fast is wasm-mcp?
It answers our handshake in 193 ms on average, which is faster than 72% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.
How many people use wasm-mcp?
The npm package wasm-mcp was installed 147 times in the last week. Week over week that is +139%. We show installs rather than GitHub stars on purpose: a star is a bookmark, an install is someone actually running it.
Is wasm-mcp open source?
The code is open source: it is published under the MIT licence, written in TypeScript and 2 stars on GitHub. The licence covers the code in the repository, not the hosted service at mcp.xyzzylabs.ai, which runs on its operator's own terms.