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API builder

When to use it
Skills for teams building on the Anthropic API — prompt caching, token budgeting, eval generation for skills, and tool-use schema writing.
Covers
Build on the Claude API (4), Build and review software (1)
Where you decide
No gated loop of its own; the skills run one at a time.
Size
4 skills · 0 loops
30–60 minutes a session
npx skilldrop-cli install --pack api-builder

Installs 4 skills.

Other ways to install

In Claude Code, as a plugin (after /plugin marketplace add sananthanarayan/skilldrop):

/plugin install api-builder@skilldrop

Into Cursor, Kiro or another IDE:

npx skilldrop-cli install --pack api-builder --ide cursor

Start here: Find where prompt caching will cut your input costs

Paste this into your agent:

Here is our system prompt and a typical request: <paste them>. Where should the cache_control breakpoints go, and what hit rate should we expect?
Before you start
  • A system prompt and a typical request from your Claude API integration
How to tell it worked
prompt-caching-advisor marks where each cache_control checkpoint goes and estimates the cache hit rate.
If nothing happens
If prompt-caching-advisor does not activate, ask for it by name and check that its folder exists in your skills folder (~/.claude/skills/ by default).

A typical session

When: You are building or tuning a Claude API integration and want its tools defined properly and its token costs under control. About 30–60 minutes.

You bring:

  1. tool-use-schema-writer
    You
    Describe each function the model should call.
    You get
    A tool_use JSON schema per function with types, required fields and parameter descriptions, and a Python client.messages.create snippet when you ask for one.
  2. token-budget-estimator
    You
    Describe the workflow or share a sample request and response.
    You get
    A per-component token table, the dominant cost driver, and max_tokens and other budget controls per component.
  3. prompt-caching-advisor
    You
    Paste the system prompt and a typical request.
    You get
    Each block classed as static, quasi-static or dynamic, where each cache_control breakpoint goes with code, and an expected cache hit rate.

You end with: Tool schemas ready to wire in, a token budget with its main cost driver named, and a caching plan.

Compare API builder with another pack

Skills in this pack (4)