forge-mcp-tool-design

Design MCP tool schemas with strict JSON Schema and retryable error contracts.

Updated Aug 23, 2026
One-click install
npx skills add https://github.com/f4rkh4d/forge-skill --skill forge-mcp-tool-design
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: forge-mcp-tool-design
Source: https://github.com/f4rkh4d/forge-skill/tree/main/skills/mcp/forge-mcp-tool-design
Command: npx skills add https://github.com/f4rkh4d/forge-skill --skill forge-mcp-tool-design

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill solves unreliable MCP tool calling by giving you a disciplined, LLM-friendly way to design tool names, descriptions, JSON Schemas, responses, and errors so models select the right tool and produce parseable outputs.

Core Features & Use Cases

  • LLM-first tool contracts: Enforces verb_object naming, third-person descriptions, and sibling-tool guidance so the model can infer when to call a tool.
  • Strict JSON Schema hygiene: Requires per-parameter descriptions, uses enums for closed sets, sets additionalProperties: false for object types, and declares ISO 8601 formats explicitly.
  • Deterministic responses & recoverable errors: Standardizes successful stable response shapes and structured error objects (code/message/retryable) so agents can retry or choose an alternate path.
  • Safety for destructive actions: Requires dry_run support for mutation/deletion patterns to reduce high-risk behavior.

Quick Start

Describe the tool you want to add to your MCP server (its verb-object name, inputs, outputs, and failure modes), then write its tool schema so every parameter has a description, object schemas include additionalProperties: false, and errors return { code, message, retryable } in a consistent structured format.

Frequently Asked Questions about forge-mcp-tool-design

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I design MCP tools so LLM agents call them correctly?

Design MCP tools with strict verb_object naming, LLM-consumable third-person descriptions, and sibling-tool guidance so the model can reliably infer usage and construct arguments. Enforce disciplined JSON Schema with descriptions on every property to resolve tool-selection ambiguity and schema-mismatch failures.

What JSON Schema rules prevent LLM function-calling argument errors?

JSON Schema hygiene for LLM function calling requires descriptions on every parameter, enums for closed sets, additionalProperties: false on object types, and explicit ISO 8601 format declarations. This strict schema discipline prevents models from generating invalid or unparseable arguments.

How should MCP tools handle errors so LLMs can retry failed function calls?

MCP tools should return structured error objects containing code, message, and retryable fields. This standardized error contract allows LLM agents to determine whether to retry the function call or select an alternate path, ensuring recoverable workflows.

Why do LLMs fail to select the right tool in MCP function-calling workflows?

LLMs fail tool selection due to ambiguous naming, missing descriptions, and unclear sibling-tool guidance. Enforcing LLM-first tool contracts with verb_object naming and third-person descriptions helps models infer exactly when to call a specific tool.

How do I add dry run support for destructive MCP tool operations?

Add dry_run support to mutation and deletion MCP tool patterns to reduce high-risk behavior. This safety mechanism allows LLM agents to validate operations before executing irreversible destructive actions.

Can I use these MCP tool design patterns for any LLM agent or only specific platforms?

These tool design patterns apply to any LLM agent that uses function calling and must reliably infer usage, construct arguments, and parse responses. The schema discipline and error contracts are platform-agnostic for all LLM function-calling workflows.