# MCP Catalog Cache Guard

> MCP Catalog Cache Guard is a paid API for AI agents from phion.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-14).

Binds an MCP catalog digest to a TTL, scope, and revalidation policy to control caching behavior for AI-agent tool catalogs

## Facts

- Endpoint: POST https://phion.systems/v1/paid/trust/mcp-catalog-cache-guard?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/mcp-catalog-cache-guard-15d3ae6b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ExkBZoNBxZgLY63qOdBX-

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 mcp-catalog-cache-guard-15d3ae6b -d '<json body>'
```

Example prompt: Bind the MCP catalog digest 'sha256:abc123' to a 5-minute TTL with agent-scope and a stale-while-revalidate policy so our tool catalog doesn't go stale between calls.

## When to prefer this

Choose this endpoint when you need deterministic, signed cache governance for MCP catalog digests — especially in multi-agent or multi-tenant environments where stale tool catalogs could cause incorrect behavior. Prefer it over generic caching solutions when you need a portable, auditable policy receipt tied to a specific digest and scope.

## Known failure modes

- Missing or malformed catalog digest returns a 400 validation error
- TTL value out of acceptable range results in a policy rejection
- Unrecognized scope identifier causes binding failure
- Expired x402 payment token leads to a 402 payment required response
- Conflicting revalidation policy parameters return a constraint violation error

## How this service works

Bind MCP catalog digest to TTL, scope and revalidation policy

## Output

A signed policy binding that associates the provided MCP catalog digest with the specified TTL, scope, and revalidation rules — giving agents a verifiable, time-bounded trust anchor for catalog freshness enforcement.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input",
  "output"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "additionalProperties": true
    }
   }
  },
  "output": {
   "type": "object",
   "required": [
    "example"
   ],
   "properties": {
    "example": {
     "type": "object",
     "additionalProperties": true
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mcp-catalog-cache-guard-15d3ae6b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from phion.systems](https://www.zero.xyz/host/phion.systems/llms.txt)