# ToolFit by YourAITools

> ToolFit by YourAITools is a paid API for AI agents from api.youraitools.co, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-25).

Lints and grades an AI agent's tool schema (MCP or function-calling format), reporting compatibility, token cost, confusable tool pairs, and basic prompt-poisoning findings.

## Facts

- Endpoint: GET https://api.youraitools.co/toolfit/v1/lite?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-25
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/toolfit-by-youraitools-8315477b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Ntk2lBOvU5zVS-nRTXDA8

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability toolfit-by-youraitools-8315477b
```

Example prompt: Can you lint my tool definitions against OpenAI, Anthropic, and Gemini, give me a letter grade, tell me how many tokens they use in total, and flag any confusable tool pairs? Here are my tools: [{"type":"function","function":{"name":"search_web","description":"Search the web","parameters":{"type":"object","properties":{"query":{"type":"string"}},"required":["query"]}}}]

## When to prefer this

Use ToolFit when you need a structured, multi-provider compatibility report on an agent tool list or MCP server before deployment or after changes — especially when you want a letter grade, token cost breakdown, confusable-pair detection, and a saved pin for future diffs, all in a single call. Prefer it over manual schema review or single-provider testing when your agent targets multiple LLM backends (OpenAI, Anthropic, Gemini, Bedrock, MCP).

## Known failure modes

- Unreachable MCP URL returns error without charge
- Invalid tools array format returns validation error without charge
- More than 500 tools in the array exceeds the limit
- Missing required 'input' parameter returns 400
- Unsupported provider enum value returns validation error

## How this service works

AI agent tool schema linter API (MCP and function calling). Check an agent tool list (tools array or public remote MCP URL): grade A-F, estimated tokens per tool and total, compatible yes/no for OpenAI, Anthropic, Gemini, Bedrock and MCP, the top confusable tool pairs, basic poisoning count and a pin (set_id) for later diffs. Bad input or an unreachable URL: never charged.

## Output

A JSON object containing: a letter grade (A–F) and numeric score (0–100), total tool count, average and total token estimates, per-provider compatibility (compatible true/false plus error counts) for OpenAI, Anthropic, Gemini, Bedrock, and MCP, a count of high-severity confusable tool pairs, basic prompt-poisoning findings (high/findings counts), and a pin (set_id) for later diffing.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "url": {
       "type": "string",
       "description": "Public remote MCP server URL (Streamable HTTP, https), e.g. https://api.youraitools.co/mcp/hub. ToolFit only lists its tools."
      },
      "tools": {
       "type": "array",
       "items": {
        "type": "object"
       },
       "description": "Tool definitions: MCP tools/list entries, OpenAI {type:\"function\",function:{...}}, Anthropic {name,description,input_schema}, Gemini functionDeclarations or Bedrock toolSpec. Max 500."
      },
      "providers": {
       "type": "array",
       "items": {
        "enum": [
         "openai",
         "openai_strict",
         "anthropic",
         "gemini",
         "bedrock",
         "mcp"
        ],
        "type": "string"
       },
       "description": "Providers to check (default openai, anthropic, gemini, bedrock, mcp; add openai_strict for Structured Outputs strict mode). GET: comma list."
      }
     },
     "description": "Search intents: mcp tool linter, function calling schema check, tool definition validator, openai tools compatibility, tool token cost, mcp audit"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "pin": {
       "type": "object"
      },
      "grade": {
       "type": "string"
      },
      "score": {
       "type": "number"
      },
      "tools": {
       "type": "number"
      },
      "tokens": {
       "type": "object"
      },
      "poisoning": {
       "type": "object"
      },
      "providers": {
       "type": "object"
      },
      "confusable": {
       "type": "object"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "pin": {
   "set_id": "ts_0123456789abcdef0123456789abcdef"
  },
  "grade": "D",
  "score": 62,
  "tools": 31,
  "tokens": {
   "avg": 374,
   "total": 11585
  },
  "poisoning": {
   "high": 0,
   "findings": 0
  },
  "providers": {
   "gemini": {
    "errors": 9,
    "compatible": false
   },
   "openai": {
    "errors": 8,
    "compatible": false
   },
   "anthropic": {
    "errors": 0,
    "compatible": true
   }
  },
  "confusable": {
   "high": 1,
   "count": 5
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/toolfit-by-youraitools-8315477b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.youraitools.co](https://www.zero.xyz/host/api.youraitools.co/llms.txt)