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MCP

Published Jul 14, 2026·Updated Aug 30, 2026

![](https://cohesivity.ai/authors/shouryamaan.webp)![](https://cohesivity.ai/authors/anshu.webp)[Shouryamaan](https://www.linkedin.com/in/shouryamaanjain/) and [Anshu](https://www.linkedin.com/in/aanshuaggrawal120/)

# MCP Tool Design Compared: Composio, Arcade.dev, and Building Your Own

[Read as Markdown](https://cohesivity.ai/blog/mcp-tool-design-compared-composio-arcade-devtools.md)

Managed

Platform

Auth

Custom

Tool

Routing

Use Composio for broad third-party SaaS actions, Arcade for authenticated tool execution, RapidMCP for wrapping existing REST endpoints, and custom MCP tools for product-specific workflows that need exact semantics. A product can use more than one approach because these platforms solve different integration problems.

Classify the required tools before comparing feature counts. A Gmail action and a proprietary billing decision should not share a make-or-buy answer.

## What each approach optimizes

### Composio

Composio provides a large catalog of third-party application toolkits plus managed authentication, connected accounts, triggers, logs, and session-based discovery. Its [session documentation](https://docs.composio.dev/docs/how-composio-works) scopes the user, tool access, authentication, connected accounts, and execution state for one agent run.

Use it when the product needs many common SaaS actions such as GitHub, Slack, Gmail, Notion, or CRM operations. Restrict sessions to the toolkits and actions the workflow needs instead of exposing the complete catalog.

### Arcade

Arcade focuses on authenticated agent tools and the per-user authorization needed to execute them. Its [documentation](https://docs.arcade.dev/en/get-started/about-arcade) covers tool development, user authentication, authorization, and execution.

Use it when acting on behalf of individual users is the central integration problem and the team wants a managed authorization and tool runtime.

### RapidMCP

RapidMCP maps REST endpoints into hosted MCP tools and configures authentication, headers, arguments, and triggers. Its [overview](https://docs.rapid-mcp.com/docs) explicitly describes a one-tool-to-one-endpoint mapping.

Use it for a quick wrapper around a small, already well-designed API. Review the generated boundary carefully. A one-to-one conversion can expose internal endpoints rather than the task-level tools a model should select.

### Custom MCP tools

Build the tool layer when the workflow is core product behavior, combines several internal services, requires strict data placement, or needs exact authorization, idempotency, and result contracts.

The cost is ownership. The team implements protocol updates, auth, deployment, observability, evaluation, and incident response. The [REST-to-MCP tutorial](https://cohesivity.ai/blog/how-to-turn-any-rest-api-into-an-mcp-server) shows the smallest useful custom starting point.

## Compare by the tool class

| Need                             | Strong starting option | Review closely                                           |
| -------------------------------- | ---------------------- | -------------------------------------------------------- |
| Many common SaaS integrations    | Composio               | Session toolkit scope, connected accounts, and data path |
| Per-user authenticated execution | Arcade                 | Provider scopes, consent, and resource authorization     |
| Small existing REST API          | RapidMCP               | One-endpoint mappings and result shaping                 |
| Proprietary business workflow    | Custom MCP             | Protocol maintenance and operations                      |
| Mixed product                    | Combination            | Duplicate auth, overlapping tools, and split logs        |

This is a fit map, not a claim that one vendor cannot support another row.

## Questions that expose the real difference

### Who owns the user connection?

Determine where OAuth client credentials, refresh tokens, scopes, revocation, and account selection live. Then inspect whether the tool receives a user-bound credential or a shared service credential.

### What does the model see?

Export the exact tool names, descriptions, and schemas. A large catalog may use runtime discovery to avoid putting every tool in context. A generated wrapper may expose every endpoint. Evaluate the actual list presented for one task.

### Where does tool data travel?

Record which vendor services receive arguments, results, files, and credentials. Compare that path to customer data requirements. A hosted connector and a self-operated MCP server have different trust boundaries even when the tool schema matches.

### Can the tool preserve business semantics?

A product-specific tool may need to join several APIs, enforce tenant rules, reconcile an operation, and return a narrow result. If the platform forces a one-endpoint mapping, keep that tool custom or place a task-level API behind the wrapper.

The [task-level tool guide](https://cohesivity.ai/blog/why-semantic-apis-are-better-for-ai-agents) provides the contract to evaluate.

## Where Cohesivity fits

Cohesivity provides backend resources through an agent-facing control and data plane. It is not a catalog of Gmail or Slack actions. A Composio, Arcade, RapidMCP, or custom tool can call a backend hosted or provisioned through Cohesivity.

Keep the layers separate in the decision. The connector decides how an agent reaches a capability. Cohesivity may provide the database, storage, hosting, email, or other backend the capability uses.

## Run a classified inventory

List every planned tool and assign it to common SaaS action, per-user auth action, REST wrapper, or product-specific workflow. Compare platforms within each row. Keep core authorization and business decisions custom unless a vendor contract matches them exactly.

The prompt below creates that make-or-buy brief from the repository without integrating anything.

or send it to[Claude Code](https://claude.ai/new?q=Inventory+the+agent+tools+this+product+needs+and+classify+each+as+a+common+third-party+SaaS+action%2C+per-user+authenticated+action%2C+existing+REST+endpoint+wrapper%2C+or+product-specific+workflow.+Do+not+integrate+a+vendor.+Compare+current+Composio%2C+Arcade%2C+RapidMCP%2C+and+custom+MCP+options+using+first-party+docs+for+tool+coverage%2C+user+auth%2C+session+scope%2C+schema+control%2C+execution+logs%2C+data+path%2C+deployment%2C+and+lock-in.+Recommend+one+approach+per+tool+class%2C+not+one+vendor+for+the+entire+project.+Identify+which+business-critical+tools+should+remain+custom+and+where+Cohesivity+would+sit+only+as+the+backend+behind+them. "Send to Claude")[Cursor](https://cursor.com/link/prompt?text=Inventory+the+agent+tools+this+product+needs+and+classify+each+as+a+common+third-party+SaaS+action%2C+per-user+authenticated+action%2C+existing+REST+endpoint+wrapper%2C+or+product-specific+workflow.+Do+not+integrate+a+vendor.+Compare+current+Composio%2C+Arcade%2C+RapidMCP%2C+and+custom+MCP+options+using+first-party+docs+for+tool+coverage%2C+user+auth%2C+session+scope%2C+schema+control%2C+execution+logs%2C+data+path%2C+deployment%2C+and+lock-in.+Recommend+one+approach+per+tool+class%2C+not+one+vendor+for+the+entire+project.+Identify+which+business-critical+tools+should+remain+custom+and+where+Cohesivity+would+sit+only+as+the+backend+behind+them. "Send to Cursor")[Codex](https://chatgpt.com/codex?prompt=Inventory+the+agent+tools+this+product+needs+and+classify+each+as+a+common+third-party+SaaS+action%2C+per-user+authenticated+action%2C+existing+REST+endpoint+wrapper%2C+or+product-specific+workflow.+Do+not+integrate+a+vendor.+Compare+current+Composio%2C+Arcade%2C+RapidMCP%2C+and+custom+MCP+options+using+first-party+docs+for+tool+coverage%2C+user+auth%2C+session+scope%2C+schema+control%2C+execution+logs%2C+data+path%2C+deployment%2C+and+lock-in.+Recommend+one+approach+per+tool+class%2C+not+one+vendor+for+the+entire+project.+Identify+which+business-critical+tools+should+remain+custom+and+where+Cohesivity+would+sit+only+as+the+backend+behind+them. "Send to Codex")[opencode](https://opencode.ai/?q=Inventory+the+agent+tools+this+product+needs+and+classify+each+as+a+common+third-party+SaaS+action%2C+per-user+authenticated+action%2C+existing+REST+endpoint+wrapper%2C+or+product-specific+workflow.+Do+not+integrate+a+vendor.+Compare+current+Composio%2C+Arcade%2C+RapidMCP%2C+and+custom+MCP+options+using+first-party+docs+for+tool+coverage%2C+user+auth%2C+session+scope%2C+schema+control%2C+execution+logs%2C+data+path%2C+deployment%2C+and+lock-in.+Recommend+one+approach+per+tool+class%2C+not+one+vendor+for+the+entire+project.+Identify+which+business-critical+tools+should+remain+custom+and+where+Cohesivity+would+sit+only+as+the+backend+behind+them. "Send to OpenCode")