A general tool for calling REST APIs, which are web endpoints used to exchange data or trigger actions. It can use an API description document or call a specified endpoint directly.

Sending GET, POST, PUT, and DELETE requests, supplying API-key or Bearer authentication, handling JSON, and inspecting OpenAPI or Swagger endpoints.

It removes the need to write one-off request code for each service. It also helps discover available operations from OpenAPI or Swagger specifications.

api-caller — Skill for Claude Code and Codex by NVIDIA/SkillEvaluator

About the project

NVIDIA/SkillEvaluator is a framework for checking and evaluating AI-agent skills, which are instruction folders that extend an agent's behavior. Skill authors and agent developers use it to validate quality and security, detect overlap, generate evaluation data, and measure skills through live agent tests. The catalogue entries are skills for running these evaluation workflows.

NVIDIA/SkillEvaluator · 585 stars · on GitHub · docs.nvidia.com

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add NVIDIA/SkillEvaluator --skill api-caller

Clone the repo

git clone --depth 1 https://github.com/NVIDIA/SkillEvaluator

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/nvidia/skillevaluator/api-caller/github.svg)](https://agentmods.dev/skills/nvidia/skillevaluator/api-caller)

Your own site

<a href="https://agentmods.dev/skills/nvidia/skillevaluator/api-caller"><img src="https://agentmods.dev/badge/skills/nvidia/skillevaluator/api-caller/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/nvidia/skillevaluator/api-caller"><img src="https://agentmods.dev/badge/skills/nvidia/skillevaluator/api-caller.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,062 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 5 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium Data Exfiltration · line 43
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
medium Data Exfiltration · line 71
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
medium Data Exfiltration · line 85
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
medium Data Exfiltration · line 92
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
medium Data Exfiltration · line 99
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00029	$0.01062
Opus 5.5	$0.00012	$0.00425
Sonnet 5.5	$0.00006	$0.00212
Haiku 4.5	$0.00003	$0.00106

Measured 1mo ago against content hash d6d3cdb62214, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

api-caller scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/call_api.py, scripts/parse_openapi.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

src/skillevaluator/tier3/reference_skills/api-caller/SKILL.md · 136 lines

How it starts

The opening of the file, as written. The whole thing — 136 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Caller Skill

Generic skill to call any REST API dynamically. Can work with OpenAPI specs or direct endpoint calls.

Capabilities

Call any REST API endpoint (GET, POST, PUT, DELETE)
Parse OpenAPI/Swagger specs to discover endpoints
Handle common authentication (API keys, Bearer tokens)
JSON request/response handling

Instructions

Read this SKILL.md to choose the direct-call or OpenAPI workflow.
Use scripts/parse_openapi.py first when the user gives an OpenAPI or Swagger spec.
Use scripts/call_api.py for the actual HTTP request.
Return the request result and any recoverable error details to the user.

Scripts

scripts/parse_openapi.py

Use this first when given an API spec URL. Parses an OpenAPI/Swagger spec and returns available operations with parameters. Run commands from the skill base directory; script paths are relative to this SKILL.md file.

Usage:

python scripts/parse_openapi.py <spec_url> [filter_path]

Arguments:

<spec_url> - URL to the OpenAPI spec (required)
[filter_path] - Optional: filter operations by path substring

Example:

python scripts/parse_openapi.py "https://api.example.com/openapi.json"

Returns: API name, base URL, and list of operations with their parameters, request body schema, etc.

scripts/call_api.py

Call a REST API endpoint directly or using an OpenAPI spec. Run commands from the skill base directory; script paths are relative to this SKILL.md file.

Usage:

python scripts/call_api.py --url <endpoint_url> [options]

Arguments:

--url <endpoint_url> - Direct API endpoint URL (required if no --spec)
--method <GET|POST|PUT|DELETE> - HTTP method (default: GET)
--data <json_string> - Request body as JSON string
--headers <json_string> - Custom headers as JSON string
--spec <openapi_url> - OpenAPI spec URL (optional, for discovery)
--operation <operation_id> - Operation ID from OpenAPI spec
--params <json_string> - Path/query parameters as JSON

Read the full file on GitHub · 136 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

1mo ago First seen · 136 lines · 29 tokens per session scan A d6d3cdb62214

Subscribe to this mod's changes

api-caller is a skill published in the GitHub repository NVIDIA/SkillEvaluator (585 stars, last pushed today), licensed Apache-2.0. It adds 29 tokens to every session and 1,062 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Backend and APIs Evaluation agent-evaluation agent-security agent-skills agentic-ai skills

api-caller

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Nothing flagged

How it starts

API Caller Skill

Capabilities

Instructions

Scripts

scripts/parse_openapi.py

scripts/call_api.py

What ships with it

What this file has done since we first saw it

Other skills, from other repositories

agent-ready-auth-md

agent-ready-dns-aid

agent-ready-link-headers

agent-ready-markdown-negotiation

agent-ready-oauth-discovery

agent-ready-oauth-protected-resource