---
name: using-services
description: >-
Discover and invoke HTTP/MCP services already registered in the global
catalog. Use when the user asks the Agent to call an API, search for an
existing service, or query a backend that was registered via the
registering-services skill. 调用某个 API、查找已有服务、访问已注册的后端服务时使用。
version: 1.0.2
type: meta
risk_level: low
status: enabled
disable-model-invocation: true
tags:
- service
- catalog
- http
- mcp
- meta
metadata:
author: desirecore
updated_at: '2026-06-29'
i18n:
default_locale: en-US
source_locale: zh-CN
locales:
- zh-CN
- en-US
zh-CN:
name: 使用服务
short_desc: 发现并调用全局目录中已注册的服务
description: >-
发现并调用全局应用与服务目录中已经注册过的 HTTP/MCP 服务。Use when 用户让 Agent 调用某个 API、查找已有服务，或访问通过 registering-services 注册的后端。
body: ./SKILL.zh-CN.md
translated_by: human
en-US:
name: Using Services
short_desc: Discover and invoke registered services from the catalog
description: >-
Discover and invoke HTTP/MCP services already registered in the global catalog. Use when the user asks the Agent to call an API, search for an existing service, or query a backend that was registered via the registering-services skill.
body: ./SKILL.md
translated_by: human
source_hash: sha256:8a20b2835e5e54d1
market:
icon: >-
category: productivity
maintainer:
name: DesireCore Official
verified: true
channel: latest
---
# using-services Skill
## L0: One-line Summary
Teach the Agent how to look up and call services from the global
"Apps & Services" catalog.
## L1: Overview
The "Apps & Services" catalog stores all registered HTTP/MCP services. This
meta-skill is your manual for **finding** the right service and **invoking**
it correctly. Each non-trivial registered service also has its own
`svc-` Skill auto-generated from its operations — prefer that when it
exists; this meta-skill is the fallback for ad-hoc discovery.
### When to use
- The user asks you to do something that might already have a registered service
(e.g. "search the product database", "send a notification")
- You see `svc-` Skill in your available skills list — activate it directly
- You need to call an HTTP API and want to check if it's been registered (to
benefit from governance, credential injection, and audit)
### When NOT to use
- The user gives you a one-off URL to fetch — use `HttpRequest` directly
- You already have the per-service `svc-` Skill activated — follow it
instead, it's more specific
## L2: How to discover and call
### Step 1 — List the catalog
Fetch the registry:
```yaml
tool: HttpRequest
parameters:
url: http://127.0.0.1:/api/registry/services
method: GET
```
Response shape (excerpt):
```json
{
"data": {
"services": [
{
"id": "acme-search-api",
"name": "Acme Search API",
"protocol": "http",
"endpoint": "https://api.acme.example/search",
"tags": ["search", "products"],
"status": "online",
"origin": "agent",
"reviewStatus": "approved",
"riskLevel": "medium",
"operations": [...]
}
],
"total": 1,
"source": "official"
}
}
```
### Step 2 — Pick a candidate
Filter by `tags`, `protocol`, `name`. Important checks **before** invoking:
- `status === 'online'` → safe to call
- `status === 'offline'` / `'error'` → tell the user the service is down,
**don't** retry blindly
- `status === 'degraded'` → degrade gracefully, mention it to the user
- `reviewStatus === 'pending'` (only `origin='agent'`) → you can only call it
if `registeredBy` is you; otherwise ask the user to promote it
- `riskLevel === 'critical'` → expect a human approval prompt on every call
### Step 3 — Build the request (HTTP services)
If the service has `operations`, prefer them — they define stable contract
points. Build the URL as ``.
```yaml
tool: HttpRequest
parameters:
url: https://api.acme.example/search/v1/items?q=widget
method: GET
headers:
Authorization: "Bearer ${secrets/api-keys/acme}" # resolved at call time
```
If the service declares `auth.secretRef`, **do not** prompt the user for the
secret value during chat. The `HttpRequest` tool resolves it automatically.
### Step 4 — Build the request (MCP services)
MCP services aren't called via `HttpRequest` — they are tools exposed through
the Agent's `mcp_servers` config:
1. If you haven't added the MCP service to your Agent yet, POST to
`http://127.0.0.1:/api/agents//mcp-servers` with `{ serverId: '', config: }`
2. Next query, MCP discovery will auto-expose tools from the server
3. Call the tools by their MCP-declared names directly
### Step 5 — Handle the response
- 2xx → parse and use
- 4xx → likely a client error (bad params, missing auth); fix the request,
then retry once; if it still fails, report to the user
- 5xx → server-side problem, report `status` of the service back so the user
knows
- **Service-approval rejected** → response will contain `"decision":"rejected"`;
do not retry, ask the user how to proceed
### Step 6 — Don't fall through to raw URL fetching
If the catalog has a service for what you need, **use it**. Don't bypass
governance by calling an undeclared URL directly — `HttpRequest` will still
work, but you lose:
- Approval gating for high-risk operations
- Credential injection (you'd need to ask the user for keys yourself)
- Audit trail and `lastUsed` tracking
- Other Agents being able to reuse your call patterns
## Failure modes
- **Catalog read fails**: just fall back to direct `HttpRequest` and warn the
user that governance is bypassed.
- **No matching service**: ask the user if they want to **register** a new
one — activate `registering-services` skill.
- **`status === 'offline'`**: report the situation, suggest checking the
underlying service, **don't** call anyway.