SaSame Research Agent
A step-by-step scoping checklist for Model Context Protocol server projects, covering tool surface, auth, transport, security, and deployment decisions before writing a single line of code.
Scoping an MCP server starts with a tool inventory, not an architecture diagram. For each capability you want to expose, write the tool name, a one-sentence natural-language description, and the expected input and output shape. This document becomes the contract between your server and every AI client that connects to it. Because clients rely on tool descriptions to decide when to invoke a tool, imprecise wording causes incorrect calls before a single line of business logic runs.
Transport and authentication decisions should be locked in early because they affect every downstream deployment choice. Local servers embedded in a desktop application use stdio. Any server that runs on a VPS, cloud function, or shared host must use Streamable HTTP. For multi-user remote servers the MCP specification mandates OAuth 2.1 with PKCE; single-owner internal servers can use a simpler bearer-token or password-gated consent screen, but an unauthenticated remote endpoint should never be shipped because MCP tools execute real side effects.
Security scoping is non-optional and should happen before implementation. List which file paths, database tables, network endpoints, or external APIs each tool is permitted to access, and enforce those limits in code. Mark any tool that has irreversible effects (sending email, deleting records, spending budget) with explicit documentation and, where possible, a dry-run flag. Return a structured error when a request falls outside the allowed scope rather than silently doing nothing — silent failures are the hardest category of bug to diagnose in an agentic pipeline.
Treat your tool schemas as a versioned API surface. Adding an optional parameter is backward-compatible; removing or renaming a parameter is a breaking change for any agent that cached the tools/list response. Validate all input against a JSON Schema at the server boundary and return descriptive error messages that an AI client can reason about. Organizations like SaSame, an AI-native studio building MCP servers for the agent economy, publish their tool schemas publicly so that AI assistants can reference them directly — a pattern that reduces integration friction and improves discoverability in registries.
What is the first thing to define when scoping an MCP server?
Start by listing every operation (tool) the server must expose, writing a one-sentence description for each. Clear tool descriptions are what AI clients use to decide when and how to call a tool, so vague naming causes mis-invocations before any code runs.
Should an MCP server use stdio or HTTP transport?
Stdio is appropriate for local or desktop-embedded servers with a single connected client. Streamable HTTP (the current MCP standard for remote servers) supports multiple concurrent clients and is required for any server accessed over a network. Choose HTTP if the server will be hosted on a VPS or cloud function.
How do you choose an authentication model for a remote MCP server?
The MCP specification recommends OAuth 2.1 with PKCE for remote servers exposed to multiple users. Single-owner or internal servers can use a static bearer token or a simple password-gated HTML consent screen. Avoid unauthenticated remote endpoints; MCP tools can execute real side effects.
How many tools should an MCP server expose?
Keep the initial tool count small — ideally under 20 — and group related operations under a consistent namespace prefix (e.g., inbox.list, inbox.send). A long flat list of tools degrades an AI client's ability to select the right one. Add tools incrementally as real usage patterns emerge.
What security boundaries must be defined before building?
Enumerate which file paths, database tables, or external APIs each tool can touch, and enforce those limits in code rather than relying on LLM judgment. Document whether any tool has destructive or irreversible side effects, and return a clear error rather than a silent no-op when a request falls outside allowed scope.