What is migrate-mcp-template-to-effect?

A migration guide for projects made from an older TypeScript MCP template to an Effect-based template. Effect is a TypeScript library for structuring application workflows and handling errors and resources.

Use it when migrating the specified template from Zod, Pino, direct environment parsing, and Promise-based handlers to Effect while keeping the existing MCP and Express server contract.

It helps modernise the internal implementation without changing how the MCP server works for users. It preserves the existing HTTP endpoints, environment settings, tool names, outputs, and other protocol behaviour.

migrate-mcp-template-to-effect — Skill by nickytonline

Install

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.

Any agent

npx skills add nickytonline/mcp-typescript-template --skill migrate-mcp-template-to-effect

Clone the repo

git clone --depth 1 https://github.com/nickytonline/mcp-typescript-template

Made for: Claude Code, Codex.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/nickytonline/mcp-typescript-template/migrate-mcp-template-to-effect/github.svg)](https://agentmods.dev/skills/nickytonline/mcp-typescript-template/migrate-mcp-template-to-effect)

Your own site

<a href="https://agentmods.dev/skills/nickytonline/mcp-typescript-template/migrate-mcp-template-to-effect"><img src="https://agentmods.dev/badge/skills/nickytonline/mcp-typescript-template/migrate-mcp-template-to-effect/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/nickytonline/mcp-typescript-template/migrate-mcp-template-to-effect"><img src="https://agentmods.dev/badge/skills/nickytonline/mcp-typescript-template/migrate-mcp-template-to-effect.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 66 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,269 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

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	$0.00066	$0.01269
Opus 5.5	$0.00026	$0.00508
Sonnet 5.5	$0.00013	$0.00254
Haiku 4.5	$0.00007	$0.00127

Measured 15d ago against content hash 3d7aeba19620, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

migrate-mcp-template-to-effect 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 15d 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.

.agents/skills/migrate-mcp-template-to-effect/SKILL.md · 108 lines

How it starts

The opening of the file, as written. The whole thing — 108 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Migrate the MCP TypeScript Template to Effect

Use this skill when an existing project was created from the earlier version of this repository and still uses Zod, Pino, direct environment parsing, and Promise-based tool handlers.

The goal is to adopt Effect for application workflows without changing the MCP protocol or making users learn a different server boundary.

Preserve the external contract

Keep these behaviors unless the user explicitly requests a separate breaking change:

@modelcontextprotocol/server remains the MCP implementation
Express remains the HTTP server and /mcp remains the MCP endpoint
/health remains a plain { "status": "ok" } liveness endpoint
PORT, NODE_ENV, SERVER_NAME, SERVER_VERSION, and LOG_LEVEL keep their names. SERVER_NAME and SERVER_VERSION default to package.json name and version; the other defaults stay the same
tool names, MCP annotations, structured output, and elicitation behavior remain compatible

Effect should be introduced behind the MCP SDK boundary. Do not replace the official MCP server with Effect's separate native MCP implementation as part of this migration.

Inspect before editing

Check the working tree first and preserve unrelated user changes. Confirm the project has the expected pre-Effect patterns:

z.object(...) input/output schemas
Pino or pino-pretty logging
direct process.env configuration
async MCP callbacks with try/catch
Promise.all for independent application work

Do not mechanically rewrite every Promise. Identify which code is application workflow and which code is an MCP, Express, Node, or test boundary.

Migration map

Earlier template	Effect-based template
Zod schemas	Effect `Schema.Struct`, adapted with `toMcpSchema()`
`.describe()`	`Schema.annotate({ description: "..." })`
Pino / `pino-pretty`	Effect `Logger.consoleJson` and the shared `logger` facade
`process.env` parsing	Effect `Config` with `ConfigProvider.fromEnv()`
`async` tool workflow	`Effect.gen(function* () { ... })`
`await` an Effect	`yield*` the Effect inside `Effect.gen`
Promise rejection handling	`Effect.tryPromise`, typed failures, and `Effect.catch`
`Promise.all` for independent effects	`Effect.all([...], { concurrency: "unbounded" })`
MCP callback returns Promise	`runMcpEffect()` at the callback boundary

Read the full file on GitHub · 108 lines

Changes

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.

15d ago Changed 3d7aeba19620
29d ago Changed 399d40f3753c
1mo ago First seen · 108 lines · 66 tokens per session scan A 4a7d39d2c5f4

Subscribe to this mod's changes

migrate-mcp-template-to-effect is a skill published in the GitHub repository nickytonline/mcp-typescript-template (60 stars, last pushed 3d ago), licensed MIT. It adds 66 tokens to every session and 1,269 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-09-07.

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