Borrowing it
Nothing to install: this file belongs to lewing/helix.mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/lewing/helix.mcp/main/.squad/skills/mcp-sdk-major-upgrade/SKILL.mdgit clone --depth 1 https://github.com/lewing/helix.mcpWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/lewing/helix.mcp/mcp-sdk-major-upgrade)<a href="https://agentmods.dev/skills/lewing/helix.mcp/mcp-sdk-major-upgrade"><img src="https://agentmods.dev/badge/skills/lewing/helix.mcp/mcp-sdk-major-upgrade/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/lewing/helix.mcp/mcp-sdk-major-upgrade"><img src="https://agentmods.dev/badge/skills/lewing/helix.mcp/mcp-sdk-major-upgrade.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What 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 5.1 | $0.00039 | $0.05125 |
| Opus 5 | $0.00019 | $0.02563 |
| Sonnet 5 | $0.00008 | $0.01025 |
| Haiku 4.5 | $0.00004 | $0.00513 |
Grade A, and why
mcp-sdk-major-upgrade scanned grade A with 2 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 11d 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -s "https://api.nuget.org/v3-flatcontainer/modelcontextprotocol/index.json" Runs shell commandslowCapability
Expected in a hook, worth knowing in a rule or an instructions file.
proc = subprocess.Popen(["dotnet", "<dll>", "mcp"], stdin=PIPE, stdout=PIPE, stderr=PIPE, text=True) How it starts
The opening of the file, as written. The whole thing — 341 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Context
Applies when the ModelContextProtocol / ModelContextProtocol.AspNetCore packages get a
new major version. Complements dependency-audit (which finds the gap) — this skill is
about deciding how to cross it. Earned on the 1.4.0 → 2.2.0 migration (2026-08-20).
Both MCP packages live in Directory.Packages.props and must move in lockstep.
Patterns
1. Establish ground truth before reading anyone's analysis
Agent-written migration reports are unreliable on release metadata. Verify first — it costs seconds:
# Real versions + real publish dates
curl -s "https://api.nuget.org/v3-flatcontainer/modelcontextprotocol/index.json"
gh release list --repo modelcontextprotocol/csharp-sdk --limit 12
# The authoritative breaking-change list
gh release view v2.0.0 --repo modelcontextprotocol/csharp-sdk --json body -q .body
Two traps seen repeatedly:
- Invented dates. Reports dated the release to "today" and the old baseline to "early ". Both wrong.
- The missed servicing release. Reports enumerate the new major's releases and skip the patch on the old major (e.g. 1.4.1). That patch is the correct rollback target, not the version you were pinned to.
2. Read the SDK source, not just the release notes, for anything you'll touch
Release notes state what changed; the source states what the API now looks like. Confirm each API the repo actually uses still exists with the same shape:
# List public members of a type at the target tag
curl -s "https://raw.githubusercontent.com/modelcontextprotocol/csharp-sdk/vX.Y.Z/src/<path>.cs" \
| grep -nE "^\s*(public|\[)"
# Find files at a tag without cloning
curl -s "https://api.github.com/repos/modelcontextprotocol/csharp-sdk/git/trees/vX.Y.Z?recursive=1" \
| python3 -c "import sys,json; [print(e['path']) for e in json.load(sys.stdin)['tree'] if e['path'].startswith('src/') and 'Filters' in e['path']]"
Our standing surface to re-verify each time:
McpServerFilters.Request.CallToolFilters · WithToolsFromAssembly(Assembly?, JsonSerializerOptions?) ·
WithResourcesFromAssembly(Assembly?) · WithStdioServerTransport() · WithHttpTransport(...) ·
IProgress<ProgressNotificationValue> injection · McpServerToolAttribute · McpException.
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.
- 11d ago First seen · 341 lines · 39 tokens per session scan A 253eb2b9b2c9
mcp-sdk-major-upgrade is a skill published in the GitHub repository lewing/helix.mcp (4 stars, last pushed yesterday), licensed MIT. It adds 39 tokens to every session and 5,125 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 2 findings (makes network calls, runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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