YAML 1.2

Human-friendly data serialisation — indentation, anchors and famous footguns.

15 capabilities 7 sections reference specification

Build against it

# give your agent the catalog — no account, no install
claude mcp add provespec -- npx -y provespec-mcp

# then, from any agent session
spec_get(slug: "yaml")                → the capability tree
spec_checklist(slug: "yaml")          → the questions to answer
spec_grade(slug: "yaml", grades: [...])  → parity % + the gap list

# or just fetch it
curl https://provespec.com/catalog/yaml/spec.json

Grade every capability below as yes · partial · no · na, with a file reference as evidence. Whatever you leave ungraded counts as missing — the gap list is the work queue.

Or just paste this to your agent

Use the ProveSpec MCP server. Fetch the "yaml" spec with
spec_get, then walk spec_checklist and grade this repository against it —
one verdict per capability, each with a file reference as the note.
Call spec_grade with the results and give me the gap list as the plan.

If the server is not registered, add it first:
  claude mcp add provespec -- npx -y provespec-mcp

The specification

Structure 4

✓ Mappings, sequences and scalars
✓ Block style with significant indentation spaces only, never tabs
✓ Flow style {a: 1, b: [2, 3]} JSON is valid YAML 1.2
✓ Multiple documents separated by ---

Scalars 4

✓ Plain, single-quoted and double-quoted escape rules differ
✓ Block scalars literal | and folded > with chomping indicators
✓ Type resolution int, float, bool, null, timestamp the Norway problem: no is not false in 1.2
✓ Explicit tags override resolution !!str 1.0

Reuse 2

✓ Anchors and aliases &name / *name
✓ Merge keys <<: *defaults

Safety 2

✓ Safe load refuses arbitrary object construction the deserialisation RCE class
✓ Alias expansion is bounded billion-laughs protection

YAML 1.2

Build against it

Or just paste this to your agent

The specification

Structure 4

Scalars 4

Reuse 2

Safety 2

Errors 1

Round-trip 1

Interop 1