mcp-builder

Use when building MCP servers to integrate external APIs or services. Produces a complete Python MCP server package with single-tool action dispatcher.

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Install this agent skill to your Project

npx add-skill https://github.com/vre/flow-state/tree/main/builder-mcp

SKILL.md

MCP Builder

Python only. stdio transport only. Single tool + action dispatcher default. Do not create your own templates.

Step 0: Threshold check

Before building, verify MCP is warranted:

Single CLI command? → "Could be: curl ... | jq or a shell alias"
Existing tool covers it? → "Could be: gh, git, docker, kubectl"
One-off data fetch? → "Could be: an ad-hoc script"

If unclear, ask user. If CLI suffices: STOP.

Step 1: Gather requirements

AskUserQuestion:

question: "What domain does this MCP serve?"
header: "Domain"
options: A. "API wrapper" - Wraps an external REST/GraphQL API B. "Local service" - Interacts with local files, DBs, or system C. "Integration" - Bridges two systems

Then ask:

Domain name (e.g., "weather", "calendar", "jira")
What actions? (list, get, create, update, delete, search, etc.)
Auth method? (none, env_var, keyring)

Set ${DOMAIN} from answers.

Step 2: Generate

If answer was A (API wrapper): Read and follow ./subskills/with_api.md

Otherwise: Read and follow ./subskills/minimal_mcp.md

Step 3: Validate

bash

python3 ./scripts/validate_mcp.py "${DOMAIN}_mcp.py"

If FAIL: fix issues. If WARN: review, fix if appropriate.

Step 4: Verify