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    🧰 Tool Schema Linter

    🧰 Tool Schema Linter

    by JustHandled Labs

    Lint the function-calling tool definitions your agent exposes. Flags tools with no description, parameters missing a description or a type, overlapping or near-duplicate tools, too many tools for reliable selection, an unsafe tool exposed without a guard, required parameters missing from the schema, and free-form parameters that should be bounded with an enum. Cleaner tool schemas mean an agent that picks the right tool.

    Updated Jun 2026
    Security scanned
    Cursor

    $12

    · or 60 credits

    30-day refund guarantee

    Secure checkout via Stripe

    Included in download

    • Audit JSON schemas for missing descriptions and untyped parameters.
    • Identify overlapping function names that cause agent confusion.
    • file_read, terminal automation included
    • Ready for Cursor
    • Instant install

    Sample input

    Lint my function definitions in ./src/tools/weather.json and check if they are well-defined.

    Sample output

    Found 3 issues in weather.json:

    • [TSL002] Severity: High | Param 'unit' in 'get_weather' missing description.
    • [TSL008] Severity: Med | Param 'location' is free-form; recommend adding 'examples' or boundaries.
    • [TSL004] Severity: Low | 'get_temp' and 'get_weather' have overlapping purposes.

    About This Skill

    What it does

    The Tool Schema Linter is a specialized audit tool for developers building agentic workflows and tool-calling applications. It analyzes your JSON function definitions against a rigorous set of rules designed to prevent LLM hallucinations, "lazy" tool selection, and security risks. By scanning your schema files, it identifies missing descriptions, untyped parameters, and overlapping tool signatures that often cause agents to fail in production.

    Why use this skill

    Writing perfect function schemas for LLMs is tedious and error-prone. While a basic prompt might catch a missing comma, this skill uses a structured heuristic engine to find logical flaws, such as too many tools for a single context window or free-form parameters that should be bounded to an enum for reliability. It saves hours of debugging "why the agent didn't call the right tool" by ensuring your definitions are mathematically and semantically sound.

    Supported tools

    • Standard JSON function-calling schemas (OpenAI, Anthropic, Gemini formats)
    • Local tool definition files (.json, .tool.json)
    • Standard input streams for CI/CD integration
    • Customizable rule thresholds via reference JSON files

    Use Cases

    • Audit JSON schemas for missing descriptions and untyped parameters.
    • Identify overlapping function names that cause agent confusion.
    • Detect unsafe tool exposure before deploying to production agents.
    • Enforce consistency across large sets of tool definitions.
    • Optimize tool definitions to reduce LLM token usage and improve accuracy.

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    Security Scanned

    Passed automated security review

    Permissions

    Read Files
    Terminal / Shell

    File Scopes

    tool-schema-linter/**
    **/tools.json
    **/*tools*.json
    **/functions*.json
    **/*.tool.json
    --stdin

    Read-only. The too-many-tools threshold is configurable. Reads no environment variables and writes nothing.

    Tags

    llm-ops
    function-calling
    json-schema
    agent-dev
    linting

    Works with any agent that can read JSON and run a local Python script (Claude Code, Cursor, Codex CLI, and other SKILL.md-compatible agents). Standard library only, no install step. Read-only, no network.

    Creator

    JustHandled Labs

    JustHandled Labs builds focused agent skills for the work nobody wants to do by hand. Each one is a single repeatable job done well: catching the security and data mistakes that quietly ship, keeping docs and tests honest, gating the commands an agent is about to run, sharpening writing, and handling the founder chores around launches, outreach, and brand setup. Not generic AI productivity. Specific workflows that are easy to run, review, and repeat. Maintained by H.J. Westerfield, with a background in communications, editing, project coordination, customer support, and practical AI systems. Tools for people who want useful automation without theatrical complexity.

    Frequently Asked Questions

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