# Maxwell x402 – Block Diagnostics (HTTP 403/Block Doctor)

> Maxwell x402 – Block Diagnostics (HTTP 403/Block Doctor) is a paid API for AI agents from api.maxwellinternational.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-02).

Diagnoses why an HTTP request to a seller endpoint was blocked (e.g. 403), determining whether the block is on the client's path (IP, region, bot wall) or the seller's side, by independently requesting the seller and comparing results.

## Facts

- Endpoint: GET https://api.maxwellinternational.ai/v1/doctor/blocked?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/maxwell-x402-block-diagnostics-http-403-block-doctor-9bd676f8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_N5YYq5MSn0FK1UendRSTG

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 maxwell-x402-block-diagnostics-http-403-block-doctor-9bd676f8
```

Example prompt: I keep getting a 403 when my agent tries to hit this seller endpoint via GET — can you run a block diagnosis and tell me whether the problem is on my path (IP or region block, bot wall) or on the seller's side, and what each side actually saw?

## When to prefer this

Use this endpoint when an agent or client is experiencing HTTP 403 or other block responses from a seller endpoint and needs to determine whether the issue is on the requester's side (IP, region, bot detection) versus the seller's configuration — without attempting to bypass or circumvent the block. Prefer this over generic HTTP testing tools when you need a structured, interpretable verdict with dual-perspective comparison.

## Known failure modes

- Seller endpoint is unreachable entirely, making comparison impossible
- Block is intermittent or rate-limit-based, leading to inconsistent results
- Input method not among allowed values (GET, HEAD, DELETE), returning validation error
- Seller endpoint requires authentication headers not provided, skewing diagnosis
- Ambiguous verdict if both sides see similar responses

## How this service works

x402 Doctor for a block you hit (e.g. 403): we request the seller ourselves and say whether the block is on your path (IP, region, bot wall) or on the seller side, with what each of us saw. We never buy around a block.

## Output

Returns a JSON verdict indicating whether the block is a client-side problem (IP, region, or bot wall on the requester's path) or a seller-side problem, along with what each party observed during the independent probe. Does not attempt to circumvent or buy around the block.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "verdict": "client_problem"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/maxwell-x402-block-diagnostics-http-403-block-doctor-9bd676f8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.maxwellinternational.ai](https://www.zero.xyz/host/api.maxwellinternational.ai/llms.txt)