Output Contract Enforcer

What it does

When your agent uses it

• Checking output contract compliance
• Generating validation schemas from descriptions
• Debugging contract mismatches between nodes

Example prompts

• “validate output”
• “output contract”
• “schema validation”
• “/output-contract-enforcer”

Requirements

• Pre-approved tools (allowed-tools): Read, Write, Edit, Grep

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

1. 1Every field B requires is present in A's output schema
2. 2Types match (A produces string, B expects string)
3. 3A's output constraints are compatible with B's input constraints
4. 4If A produces optional fields that B requires → incompatible

What it can do on your machine

Read from SKILL.md and the folder at commit 6713fc7. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Write
  • Edit
  • Grep

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • node

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Output Contract Enforcer loads about 1.6k tokens when it runs. Until then it costs about 143 tokens; SKILL.md has 367 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~143

When it runs · the whole SKILL.md, loaded when a task matches

~1.6k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from curiositech/some_claude_skills at commit 6713fc7, republished under its MIT licence (© curiositech). 367 words, ~1,550 tokens.

name

output-contract-enforcer

description

Validates that a DAG node's output matches its declared JSON schema before passing to downstream nodes. The glue that makes multi-agent DAGs reliable. Use when checking output contract compliance, generating validation schemas from descriptions, or debugging contract mismatches between nodes. Activate on "validate output", "output contract", "schema validation", "contract mismatch", "output doesn't match". NOT for content quality assessment (use dag-quality), skill grading (use skill-grader), or general JSON schema work outside DAG context.

allowed-tools

Read, Write, Edit, Grep

argument-hint

[output-json] [schema]

metadata.tags

output, contract, enforcer, validate-output, output-contract

flowchart TD
  O[Node output] --> P[Parse as JSON]
  P -->|Parse error| E1[FAIL: Not valid JSON]
  P -->|Valid JSON| S[Check against schema]
  S --> R{Required fields?}
  R -->|Missing| E2[FAIL: Missing required field X]
  R -->|Present| T{Type check?}
  T -->|Wrong type| E3[FAIL: Field X expected string, got number]
  T -->|Correct| C{Constraints?}
  C -->|Violated| E4[FAIL: Field X violates constraint Y]
  C -->|Met| V[PASS: Contract satisfied]

{
  "type": "object",
  "required": ["status", "summary"],
  "properties": {
    "status": {
      "type": "string",
      "enum": ["pass", "warn", "fail"]
    },
    "summary": {
      "type": "string",
      "minLength": 1,
      "description": "1-3 sentence description of what was produced"
    },
    "artifacts": {
      "type": "array",
      "items": { "type": "string" },
      "description": "List of files created or modified"
    },
    "data": {
      "type": "object",
      "description": "Node-specific output data (schema varies per node)"
    },
    "risks": {
      "type": "array",
      "items": { "type": "string" },
      "description": "Remaining risks or assumptions"
    }
  }
}

Node A output: { status: string, recommendations: string[] }
Node B input:  { status: string, recommendations: string[], priority: number }

Result: INCOMPATIBLE — Node B requires 'priority' but Node A doesn't produce it.
Fix: Add 'priority' to Node A's output, or add a transformer node between A and B.

{
  "type": "object",
  "required": ["status", "summary", "data"],
  "properties": {
    "status": { "type": "string", "enum": ["pass", "warn", "fail"] },
    "summary": { "type": "string", "minLength": 1 },
    "data": {
      "type": "object",
      "required": ["recommendations"],
      "properties": {
        "recommendations": {
          "type": "array",
          "minItems": 1,
          "items": {
            "type": "object",
            "required": ["text", "priority"],
            "properties": {
              "text": { "type": "string" },
              "priority": { "type": "integer", "minimum": 1, "maximum": 5 }
            }
          }
        }
      }
    }
  }
}

© curiositech, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file in .claude/skills/output-contract-enforcer of curiositech/some_claude_skills.

• SKILL.md
• .claude-plugin/plugin.json

Open the folder on GitHubat commit 6713fc7