MCLIP

The problem

The MCP-to-CLI translation space is already crowded: mcp2cli, MCPorter, MCPShim, FastMCP generate-cli, Apify mcpc, IBM mcp-cli, developit/mcp-cmd, f/mcptools. Each picks its own flag conventions, command shapes, output formats, error structures, and resource/prompt surfaces.

Result: N MCP wrappers, N different CLI surfaces over the same MCP server. A script written against one wrapper does not run against another. Five concrete portability breakages span the eight wrappers: argument-passing style, JSON output flag + shape, invocation pattern, array encoding, and server reference.

MCLIP standardises the translation itself, so any conformant tool produces the same scriptable surface for the same MCP server. It is not a new protocol. It is not a vendor-side standard. It applies to the tools that translate MCP into CLI — telling them how to do it consistently.

Concretely — the same MCP tool, across wrappers:

# f/mcptools
mcp call create_issue --params '{"title":"Bug","body":"..."}' \
  npx -y @modelcontextprotocol/server-github

# Apify mcpc
mcpc @github tools-call create_issue title:="Bug" body:="..."

# Under MCLIP, every conformant wrapper:
<binary> github tools call create_issue --title "Bug" --body "..."

Different command verbs, different argument styles, different server references, different output shapes. MCLIP-Core (§1.2, §2.5, §5) pins all four.

How MCP maps to the CLI

MCLIP doesn't try to turn every MCP message into a shell command. The projection draws three lines:

MCP primitives become commands; MCP schemas become input contracts; MCP responses become a JSON envelope; MCP lifecycle and interaction mechanics become CLI runtime behaviour. The nine conformance modules in profile-v0.md §0.7 are organised around this split.

What the profile defines

MCLIP-Core plus eight independently-claimable modules. A wrapper can claim conformance on Core plus any subset of the modules its UX supports.

• MCLIP-Core Required for any conformance claim
• MCLIP-Resources First-class resources surface
• MCLIP-Prompts First-class prompts surface
• MCLIP-HTTP Standardised HTTP transport handling
• MCLIP-Streaming Resources watch as NDJSON
• MCLIP-Safety Confirmation, dry-run, force overrides
• MCLIP-Auth Token resolution and transmission
• MCLIP-Metadata Honours optional mclip.* keys
• MCLIP-Discovery Inherited config files

Specifications

Source of truth lives in the GitHub repository. The files below are the v0 draft set; everything is pre-publication and subject to revision.

• Profile v0 profile-v0.md

  Normative specification — Core plus eight independently-claimable modules. Each rule tagged [MCLIP-§-NN] for conformance tracking.

• Security Model security-model.md

  Trust boundaries, destructive-action policy, CI-safety, credential handling, optional auditability.

• Conformance Fixtures conformance-fixtures.md

  30+ executable fixtures mapping rules to invocations, expected exit codes, and output shapes.

• Adoption Guide adoption-guide.md

  For existing wrapper maintainers — minimum surface for MCLIP-Core conformance and the per-module cost.

• SEP — Standards Track sep-standards-mclip-profile.md

  Standards Track SEP draft wrapping the profile for filing under modelcontextprotocol/seps.

• SEP — Extensions Track sep-extensions-mclip-metadata.md

  Optional mclip.* metadata keys filed per SEP-2133. Tightening-only safety semantics.

• mclio Architecture mclio-architecture.md

  Implementation spec for the production CLI that doubles as the standard's executable reference.

• Fixtures Spec fixtures-spec.md

  Implementation spec for the nine synthetic MCP servers backing the conformance fixture catalogue.

Schema namespace

The canonical MCLIP config schema is hosted under mclip.dev. Clients and editors validating an mclip.json file should reference the versioned URL below.

https://mclip.dev/schemas/config/v0.json

Draft 2020-12 JSON Schema. Tracks profile-v0.md §13.3. The schema URL is normatively cited from the profile; the schema body is hand-maintained against the spec until automated generation lands.

Current status

The specification set is written and internally consistent. The nine synthetic MCP fixture servers and the verify harness are built (Go, MCP SDK v1.6.0; under fixtures/). mclio — the production CLI that doubles as the standard's executable reference — is in active development as a separate Go binary; not yet released. Conformance harness and a companion consumer app follow once mclio is functional.