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wasm-mcp

NPM · WASM-MCP · 2 COMPONENTS · SCANNED SEP 20

Read-only MCP server for the WebAssembly spec: instructions, types, sections, search, proposals.

Available components

remote · mcp.xyzzylabs.ai 76 npm · wasm-mcp 92
0 this week 92 Trust /100
Trust breakdown (7 categories)

How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. How we score → Why this is hard to score →

Supply Chain Security98
  • No malware found by supply-chain analysis.Pass
  • No known CVEs affecting this package version or its production dependencies.Pass
  • No install/post-install scripts declared.Pass
  • 31 of 95 dependencies flagged as unhealthy. View diagnostics → Partial
Provenance & Transparency100
  • Source repository is publicly reachable at the declared URL. View diagnostics → Pass
  • Cryptographically verified build provenance (signed, bound to xyzzylabs/wasm-mcp). View diagnostics → Pass
  • Clear OSI-approved license (MIT).Pass
  • Actively maintained (last published 70 days ago).Pass
  • Publishes a security disclosure policy (SECURITY.md).Pass
Schema Quality & AI Usability65
  • AI-judged instruction clarity (excellent).Pass
  • Context-footprint check failed: tool/resource definitions use about 2807 tokens (~311/item across 9 items; 9 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
  • Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management93
  • Stability observed for 28 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage100
  • 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
  • 100% of tool parameters carry a description.Pass
Tool Safety100
  • No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
  • We read all 9 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
  • An AI judge read all 10 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
  • Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.Pass
Install

How do I install the wasm-mcp server?

wasm-mcp runs locally as an npm package, launched with npx -y wasm-mcp. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

npm · wasm-mcp

# add to Claude Code
claude mcp add xyzzylabs-wasm-mcp -- npx -y wasm-mcp
// .cursor/mcp.json
{
  "mcpServers": {
    "xyzzylabs-wasm-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "wasm-mcp"
      ]
    }
  }
}
// .vscode/mcp.json
{
  "servers": {
    "xyzzylabs-wasm-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "wasm-mcp"
      ]
    }
  }
}
# add to Codex CLI
codex mcp add xyzzylabs-wasm-mcp -- npx -y wasm-mcp
// opencode.json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "xyzzylabs-wasm-mcp": {
      "type": "local",
      "command": [
        "npx",
        "-y",
        "wasm-mcp"
      ],
      "enabled": true
    }
  }
}
# add to OpenClaw
openclaw mcp add xyzzylabs-wasm-mcp --command npx --arg -y --arg wasm-mcp
# ~/.hermes/config.yaml
mcp_servers:
  xyzzylabs-wasm-mcp:
    command: "npx"
    args: ["-y", "wasm-mcp"]
// ~/.netclaw/config/netclaw.json
{
  "McpServers": {
    "xyzzylabs-wasm-mcp": {
      "Transport": "stdio",
      "Command": "npx",
      "Arguments": [
        "-y",
        "wasm-mcp"
      ]
    }
  }
}
# add to Vellum
assistant mcp add xyzzylabs-wasm-mcp -t stdio -c npx -a -y wasm-mcp
// mcp.json
{
  "mcpServers": {
    "xyzzylabs-wasm-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "wasm-mcp"
      ]
    }
  }
}
Changelog

Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.

  • 19 Sept 26 +1

    No change was recorded against any check on this day. Stability & Change Management went from 87 to 90. That category is still filling its 30-day observation window: 26 days of observed history at the previous scan, 27 at this one. The score rises as the window fills, whether or not the server changes.

  • 17 Sept 26 −2
    • Stability: pass → 0.83 functional
  • 16 Sept 26 0
    • Stability: 0.97 → pass security
  • 15 Sept 26 +1

    No change was recorded against any check on this day. Stability & Change Management went from 93 to 97. That category is still filling its 30-day observation window: 28 days of observed history at the previous scan, 29 at this one. The score rises as the window fills, whether or not the server changes.

  • 13 Sept 26 +1

    No change was recorded against any check on this day. Stability & Change Management went from 87 to 90. That category is still filling its 30-day observation window: 26 days of observed history at the previous scan, 27 at this one. The score rises as the window fills, whether or not the server changes.

  • 11 Sept 26 +1

    No change was recorded against any check on this day. Stability & Change Management went from 80 to 83. That category is still filling its 30-day observation window: 24 days of observed history at the previous scan, 25 at this one. The score rises as the window fills, whether or not the server changes.

  • 10 Sept 26 −3
    • Stability: pass → 0.80 functional
  • 9 Sept 26 0
    • Stability: 0.97 → pass security
Diagnostics

Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.

Captured 20 Sept 2026 · Analysed npm/wasm-mcp@0.2.16

Provenance Verified

A signed build attestation was found and verified, binding this exact artifact to the source repository it claims to come from.

Result Verified
Ecosystem npm
Reason Verified
Discovered via Registry attestation endpoint
Source repo xyzzylabs/wasm-mcp
Certificate issuer https://token.actions.githubusercontent.com
Certificate SAN https://github.com/xyzzylabs/wasm-mcp/.github/workflows/release.yml@refs/tags/v0.2.16
Rekor log index 2141972031
Predicate type https://slsa.dev/provenance/v1
Subject digest sha512:da6f271127abb550827a0f1413af8b67172c7e1df399051745d97bc06ba3c55d05a9588f908007040f6f1e6fe42536de6d8c89aed7209ef751424908b

Background: How many MCP packages publish verified provenance →

Dependencies 95 packages
Packages resolved 95
Stale 31
Tree resolution Complete

Background: SBOMs and build attestations, explained →

MCP tools · 9 exposed · ~2,070 tokens

The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →

Tool Tokens
instruction_get ~246

Fetch one WebAssembly instruction by mnemonic (`i32.add`, `br_if`) or binary opcode (`0x6a`, `0xfd 0x89 0x02`) as structured JSON: opcode bytes, category, introducing version, stack type signature, validation/execution prose anchors + spec URLs, and `traps` — the runtime conditions under which it traps (each with the spec's canonical trap name; empty + `can_trap: false` for instructions that never trap). Provide `mnemonic` or `opcode` (mnemonic wins if both match).

NameTypeReqDescription
mnemonicstring–Instruction mnemonic, e.g. `i32.add`, `br_if`, `local.get`. Case-insensitive. Exact match.
opcodestring–Binary opcode as hex bytes, e.g. `0x6a`, `6a`, or multi-byte `0xfd 0x89 0x02`. Exact match. Used when `mnemonic` is absent or doesn't match.
versionstring–WebAssembly spec version to query. `latest` (default) is the current served version; `main` is the upstream working draft.

No output schema declared.

No examples provided.

instruction_list ~311

Enumerate WebAssembly instructions with optional filters: `category` (control, numeric, parametric, variable, table, memory, ref, i31, struct, array, extern, vec), `introduced_in` (1.0 | 2.0 | 3.0), `prefix` (mnemonic prefix like `i32.`), and `can_trap` (only trapping / only non-trapping instructions). Returns lightweight rows (incl. `can_trap`) sorted by opcode; follow up with instruction_get for full detail incl. trap conditions.

NameTypeReqDescription
can_trapboolean–Filter by trapping behavior: `true` keeps only instructions that can trap at runtime, `false` keeps only those that never trap. See instruction_get for the per-instruction trap conditions.
categorystring–Filter by instruction category: control, numeric, parametric, variable, table, memory, ref, i31, struct, array, extern, vec (vector/SIMD).
introduced_instring–Filter to instructions introduced in this WebAssembly version: `1.0`, `2.0`, or `3.0`.
prefixstring–Filter to mnemonics starting with this prefix, e.g. `i32.` or `v128.`. Case-insensitive.
versionstring–WebAssembly spec version to query. `latest` (default) is the current served version; `main` is the upstream working draft.

No output schema declared.

No examples provided.

instruction_search ~150

Search WebAssembly instructions by free-text query, matched against mnemonic (exact > substring), category name, and opcode hex. The entry point when you don't know the exact mnemonic. Returns ranked lightweight hits with a `matched_on` field; follow up with instruction_get.

NameTypeReqDescription
limitinteger–Max ranked hits returned.
querystringyesSearch text. Matched against mnemonic (exact > substring), category name, and opcode hex. E.g. `extend`, `trunc`, `vec`, `0x6a`.
versionstring–WebAssembly spec version to query. `latest` (default) is the current served version; `main` is the upstream working draft.

No output schema declared.

No examples provided.

proposal_list ~217

List WebAssembly proposals and their phases from the pinned WebAssembly/proposals repository. Filter by `status` (phase-0…phase-5, finished, inactive), `phase` (0–5), `champion` substring, `affects` (finished proposals touching core / js-api / web-api), or `contains` (name/champion substring). Each row carries name, status, phase, champion, affected_specs, spec_version, and the proposal URL.

NameTypeReqDescription
affectsstring–Filter to finished proposals affecting a given spec: `core`, `js-api`, or `web-api`.
championstring–Champion substring, case-insensitive.
containsstring–Name or champion substring, case-insensitive.
phaseinteger–Filter by numeric phase 0–5 (active + finished proposals carry a phase).
statusstring–Filter by lifecycle status: `phase-0`…`phase-5`, `finished` (merged into the spec), or `inactive`.

No output schema declared.

No examples provided.

section_get ~286

Fetch one spec clause by id or anchor, across `core` / `js-api` / `web-api` (set `spec`). For core: `syntax-numtype`, `valid-unreachable`, `binary-instr`, … For the embedding specs: `modules`, `memories`, `streaming-modules`, … Matches the rendered spec's stable fragment ids. Returns the clause title, cleaned prose, cross-references, the SpecTec `formal_refs` it cites (core), and the rendered URL. Core validation/execution clauses are SpecTec-generated: prose may be terse, but formal_refs + url point to the formal rule.

NameTypeReqDescription
idstringyesClause id or anchor. For `core`: `syntax-numtype`, `valid-unreachable`, `binary-instr`, … For `js-api` / `web-api`: `modules`, `memories`, `streaming-modules`, … These match the stable fragment ids i…
specstring–Which WebAssembly spec to query: `core` (default; instructions, types, validation, execution, formats), `js-api` (JavaScript embedding), or `web-api` (Web platform integration).
versionstring–WebAssembly spec version to query. `latest` (default) is the current served version; `main` is the upstream working draft.

No output schema declared.

No examples provided.

section_list ~330

Enumerate spec clauses for navigation, across `core` / `js-api` / `web-api` (set `spec`). Filter by source `path` (core: `intro`, `syntax`, `valid`, `exec`, `binary`, `text`, `appendix`, or sub-paths like `syntax/types`), `anchor_prefix`, `titled_only`, and `max_level`. Returns lightweight rows {id, anchors, title, level, path, url}; follow up with section_get.

NameTypeReqDescription
anchor_prefixstring–Filter to clauses whose id/anchor starts with this prefix, e.g. `syntax-`, `valid-`, `exec-`.
max_levelinteger–Cap heading depth (1 = page titles only). Anchor-only blocks are unaffected.
pathstring–Filter to a source path / prefix. Top-level areas: `intro`, `syntax` (structure), `valid` (validation), `exec` (execution), `binary`, `text`, `appendix`. Sub-paths like `syntax/types` also work.
specstring–Which WebAssembly spec to query: `core` (default; instructions, types, validation, execution, formats), `js-api` (JavaScript embedding), or `web-api` (Web platform integration).
titled_onlyboolean–Drop anchor-only content blocks (keep only clauses with a heading).
versionstring–WebAssembly spec version to query. `latest` (default) is the current served version; `main` is the upstream working draft.

No output schema declared.

No examples provided.

spec_search ~227

Full-text search across the section index of a spec (`core` / `js-api` / `web-api`, set `spec`) — clause anchors/ids, titles, and prose. The entry point when you don't know the exact anchor. Returns ranked hits with a `matched_on` field (anchor-exact > title > anchor > prose) and a prose snippet for body matches; follow up with section_get.

NameTypeReqDescription
limitinteger–Max ranked hits returned.
querystringyesSearch text. Matched against clause anchors/ids, titles, and prose. E.g. `block type`, `trap`, `funcref`, `streaming compilation`.
specstring–Which WebAssembly spec to query: `core` (default; instructions, types, validation, execution, formats), `js-api` (JavaScript embedding), or `web-api` (Web platform integration).
versionstring–WebAssembly spec version to query. `latest` (default) is the current served version; `main` is the upstream working draft.

No output schema declared.

No examples provided.

spec_version ~55

Return self-description of this MCP server: package name + version, plus the pinned upstream commit SHA for every spec snapshot baked into the package. Use this first when citing the spec, or to verify the server's freshness and reproducibility.

Input schema present but exposes no named parameters.

No output schema declared.

No examples provided.

type_get ~248

Look up a WebAssembly type or type form by name: concrete value types (`i32`, `i64`, `f32`, `f64`, `v128`, `funcref`, `externref`, …) or type forms (`functype`, `limits`, `memtype`, `tabletype`, `globaltype`, `reftype`, `valtype`, `rectype`, `heaptype`, …). Returns its classification, sibling members for category types, defining clause prose, SpecTec formal-rule references, and the rendered spec URL.

NameTypeReqDescription
namestringyesType or type-form name. Concrete value types: `i32`, `i64`, `f32`, `f64`, `v128`, `funcref`, `externref`, … Type forms: `functype`, `limits`, `memtype`, `tabletype`, `globaltype`, `reftype`, `valtype…
versionstring–WebAssembly spec version to query. `latest` (default) is the current served version; `main` is the upstream working draft.

No output schema declared.

No examples provided.

Common questions

What is the wasm-mcp server?

wasm-mcp is listed in the public MCP registry as io.github.xyzzylabs/wasm-mcp. Read-only MCP server for the WebAssembly spec: instructions, types, sections, search, proposals. This page covers its npm package (wasm-mcp).

Is the wasm-mcp server safe to use?

wasm-mcp scores 92 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 20 September 2026. It declares no install or post-install scripts. Its build provenance is signed and verified. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

What tools does the wasm-mcp server expose?

wasm-mcp exposes 9 tools: spec_version, instruction_get, instruction_list, instruction_search, type_get, and 4 more. Their descriptions and schemas cost roughly 2,070 tokens of context every time the server is loaded.

Is the wasm-mcp server still maintained?

wasm-mcp is still listed as active in the MCP registry. We last reached this channel on 20 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

What licence is the wasm-mcp server under?

wasm-mcp declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.