Skillget

OnlyCLI

mcp
SUMMARY

Turn any OpenAPI spec into a native CLI binary. No MCP, no bloat, no runtime dependencies, ONLY CLI.

README.md

OnlyCLI

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License: MIT

Turn any OpenAPI spec into a complete CLI. One command. One binary. 35x fewer tokens than MCP.

OnlyCLI terminal demo: generate a CLI from the GitHub API spec, then query repos, search, and list issues

Every endpoint in the GitHub REST API (1,107 operations) becomes a typed CLI command with flags, help text, and shell completion.

Install

go install github.com/onlycli/onlycli/cmd/onlycli@latest

Or download a pre-built binary from Releases.

Quick Start

# 1. Generate -- point at any OpenAPI 3.x spec (local file or URL)
onlycli generate \
  --spec https://raw.githubusercontent.com/swagger-api/swagger-petstore/master/src/main/resources/openapi.yaml \
  --name petstore --out ./petstore-cli

# 2. Build
cd petstore-cli && go mod tidy && go build -o petstore .

# 3. Use
./petstore pet find-pets-by-status --status available --format table
./petstore --help

That's it. Every operation in the spec is now a CLI command.

What You Get

Every generated CLI ships with:

Capability How
Every endpoint as a command Grouped by tag, named by operationId
All parameters as --flags Path, query, header, and request body fields
7 output formats --format json|yaml|table|csv|pretty|jsonl|raw
Field projection --transform "#.name" via GJSON
Go template output --template '{{.login}}'
Auto-pagination --page-limit N auto-detects Link, cursor, offset, page-number
Streaming --stream for SSE and NDJSON responses
File input --data @payload.json or --data @- for stdin
OAuth2 authentication Device flow (interactive) + client credentials (CI)
Multi-profile config config set staging.token xxx && --profile staging
Retry with backoff --max-retries 3 for transient 429/5xx errors
Dry-run mode --dry-run prints the request without sending
HTTP/2 + gzip Modern transport, automatic content decompression
Shell completion completion bash|zsh|fish|powershell with enum hints
Cross-platform Linux, macOS, Windows; amd64, arm64

Examples

Pre-generated CLIs from live public specs:

Example Source Spec Groups Commands
petstore Swagger Petstore 3 19
github GitHub REST API 43 1,107

Regenerate them yourself:

make generate-example

Comparison

OnlyCLI curl Restish MCP tools
Typed commands per endpoint Yes No Yes Varies
Single distributable binary Yes Yes Yes No
Output formatting (table/yaml/csv) Yes No No No
Multi-scheme pagination Yes No No No
Streaming (SSE/NDJSON) Yes Manual No Varies
Works offline, no server process Yes Yes Yes No
Token cost for AI agents Low Low Low High

Detailed write-ups: vs Stainless · vs Restish · vs curl/HTTPie

For AI Agents: 35x Cheaper Than MCP

A GitHub MCP server loads 55,000 tokens into every prompt. Three services consume 72% of your context window on idle. At scale, that is $51,000/month in pure schema overhead.

OnlyCLI takes the opposite approach:

  1. Generate a binary once from the spec
  2. Agent calls ./cli --help to discover commands (~200 tokens)
  3. Agent runs ./cli repos get --owner x --repo y and reads stdout

Stable command names, predictable flags, structured JSON output. No MCP server, no schema injection, no connection management. See the full cost analysis.

Development

git clone https://github.com/onlycli/onlycli.git && cd onlycli
make test          # unit + integration tests
make lint          # golangci-lint
make check         # fmt + vet + lint + test
make build         # build to bin/onlycli

See CONTRIBUTING.md for the full guide and ARCHITECTURE.md for codebase structure.

License

MIT

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