Composio is a software toolkit that gives AI agents access to authenticated tools for interacting with apps and services. Developers use its SDKs, command-line interface, sessions, and sandbox to build agents that can carry out actions. The catalogue add-ons support workflows for using Composio with coding agents.
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 skills add ComposioHQ/composio --skill effect-v4git clone --depth 1 https://github.com/ComposioHQ/composioWrote 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/composiohq/composio/effect-v4)<a href="https://agentmods.dev/skills/composiohq/composio/effect-v4"><img src="https://agentmods.dev/badge/skills/composiohq/composio/effect-v4/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/composiohq/composio/effect-v4"><img src="https://agentmods.dev/badge/skills/composiohq/composio/effect-v4.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 | $0.00169 | $0.01049 |
| Opus 5 | $0.00084 | $0.00524 |
| Sonnet 5 | $0.00034 | $0.00210 |
| Haiku 4.5 | $0.00017 | $0.00105 |
Grade A, and why
effect-v4 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 today.
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 — 73 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Effect v4
The CLI, @composio/cli-keyring, and @composio/json-schema-to-effect-schema run on
Effect v4 (release candidate). Every claim below is grounded in the migrated source, not memory of v3.
Exact version matrix
effect, @effect/platform-bun, and @effect/vitest
are pinned to the same exact 4.0.0-rc.112 — never ^, @next, or a mismatched
prerelease across packages. @effect/cli and @effect/platform no longer exist as
dependencies; their surfaces are consolidated into effect and effect/unstable/*.
See versions.json for the full matrix (also typescript, vitest).
Read next
- references/core-patterns.md — services, layers, typed
errors, Schema, choosing between
Effect.genandEffect.fn, and the v3→v4 rename table (labeled historical, for recognizing stale patterns). - references/cli-surface.md —
effect/unstable/cli:Command,Flag,Argument,GlobalFlag,CliConfig, the customCliOutput.Formatter, and the runner's double-print rule. - references/upgrade-workflow.md — procedure for bumping to a newer prerelease.
Code excerpts in those references are short quotes from real, currently-compiling repo files (path cited at each excerpt) — not standalone examples. The compile-checked source of truth is always the cited file itself; when it and a reference disagree, trust the file and fix the reference.
Non-negotiables
Effect.gen(function* () {...})for effect values — the dominant form, including named module consts — and(params) => Effect.gen(...)for parameterized helpers.Effect.fn(...)is the function form whose effects carry stack-frame annotations (its optional name string adds a per-call tracing span), worth it for service members and combinator callbacks that should be attributable in error reports. All forms re-run their body per execution. See "Effect.genvsEffect.fn" in core-patterns.- Define services with
Context.Serviceand an explicitstatic readonly Default/layerlayer built withLayer.succeed/Layer.effect/Layer.provide. V4 does not generate a layer for you. - Model expected failures with
Schema.TaggedError(or a plainData.TaggedErrorwhen no Schema fields are needed) and recover withEffect.catchTag/catchTags/Match, never manual_tagstring comparisons. - Wrap fallible Promises with
Effect.tryPromise({ try, catch });Effect.promiseturns rejection into a defect. Noasync/awaitortry/catchinside Effect workflows — ESLint bans them ints/packages/cli/src. - Treat every remembered v3 package name and API as wrong until verified against
ts/vendor/effect(read-only source oracle — never edit or import from it) and the installed[email protected]typings. Source may be ahead of the published package; the compiler is the compatibility gate.
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- today First seen · 73 lines · 169 tokens per session scan A 48426caddc3b
effect-v4 is a skill published in the GitHub repository ComposioHQ/composio (30,136 stars, last pushed today), licensed MIT. It adds 169 tokens to every session and 1,049 once invoked, about $0.0008 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 2026-09-12.
Other skills, from other repositories
mcp-server-patterns
Build MCP servers with Node and TypeScript using tools, resources, Zod schemas, and stdio transport.
coding-standards
Universal coding standards, best practices, and patterns for TypeScript, JavaScript, React, and Node.js development.
bun-runtime
Bun as runtime, package manager, bundler, and test runner. When to choose Bun vs Node, migration notes, and Vercel support.
chat-sdk
Build multi-platform chat bots with Chat SDK (chat npm package). Use when developers want to (1) Build a Slack, Teams, Google Chat, Discord, Telegram, GitHub, Linear, or WhatsApp bot, (2) Use Chat SDK to handle mentions, direct messages, subscribed threads, reactions, slash commands, cards, modals, files, or AI…
typescript
TypeScript coding conventions, best practices, and patterns for writing clean, maintainable code.
typescript
TypeScript strict mode with eslint and jest.