> ## Documentation Index
> Fetch the complete documentation index at: https://docs.markapidown.net/llms.txt
> Use this file to discover all available pages before exploring further.
# API Testing for AI Coding Agents
> Use Reqbook with Claude Code, Cursor, Copilot, Codex CLI, Antigravity, OpenCode, and Windsurf to read, write, validate, and run API specs.
# Reqbook makes agents API-capable.
Agents are great at writing code but struggle with API work — they can't reliably run requests from inside the session, produce API specs that stay in sync with the code, or review results in a structured way.
Reqbook gives agents the building blocks they need: markdown files they can read and write, tools that return structured results, and playbooks that know when to call the CLI and when to use LLM reasoning.
A single markdown playbook that teaches agents the spec format, file layout, and decision trees — installed to the directory each agent reads from automatically.
Two `/rqb` commands for the complex, LLM-native tasks: spec creation and enrichment, flow building, and debugging.
Ten structured tools for MCP-compatible agents — exec, diagnose, flow, author, vars, search, context, history, session, and exec\_batch. Surgical context by default.
Every agent change is a markdown file in `api-docs/`. Reviewable, diffable, committable. No hidden state.
***
## The division of labor
The key design decision: not every operation needs an agent. Simple, deterministic operations belong in the terminal. Agents add value when a task requires reasoning about your codebase, your domain model, or the relationships between data.
| Operation | Where | Why |
| ----------------------------------- | ---------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| Init, serve, validate, exec, mock | Terminal | Fast, composable, no LLM needed |
| Scan routes and create specs | `/rqb` | Needs to read source types and infer realistic field values |
| Enrich expected responses and tests | `/rqb enrich` | Needs to understand field semantics, volatile vs stable values, domain edge cases |
| Build a workflow pipeline | `/rqb flow` | Needs to reason about data dependencies between steps |
| Debug a failing endpoint or flow | `/rqb-debug` | Multi-step diagnosis with contextual interpretation |
| Execute a spec (structured result) | `rqb_exec` MCP | Returns compact JSON — pass `verbose: true` for full payloads |
| Diagnose a failed endpoint | `rqb_diagnose` MCP | Returns likely cause, next action, inspect targets, and verify commands before broad source reading |
| Dry-run (resolve vars, don't send) | `rqb_exec` + `dry_run: true` | Catches missing variables before hitting the network |
| Check variable readiness | `rqb_vars` MCP | Shows what's resolved and what's missing before exec |
| Search specs by method/tag/path | `rqb_search` MCP | Compact index — no file reading required |
| Build surgical API context | `rqb_context` MCP | Gives the agent method/path, bounded body fields, response fields, error cases, assertions, and verify commands instead of many source files |
| Run a pipeline (structured result) | `rqb_flow` MCP | Returns per-step state for programmatic debugging |
| Author a spec (with write guard) | `rqb_author` MCP | Validates before writing, refuses silent overwrites |
| Check execution trend | `rqb_history` MCP | Stable/improving/regressing over recent runs |
| Set session defaults | `rqb_session` MCP | Set env + vars once; all exec/flow calls inherit |
| Run multiple specs | `rqb_exec_batch` MCP | Summary table — not N full JSON objects |
***
## Skills — all agents
Skills are the "always-on" layer: installed to each agent's config directory, they activate automatically when API-related topics come up in the conversation. No explicit command needed.
One skill covers the full workflow:
* **rqb** — Project layout, endpoint spec format, Assertions operators, pipeline capture patterns, MCP tool reference, and routing rules for when to use each slash command.
Installed via `rqb skills install` to agent-specific locations (`.claude/skills/`, `.cursor/rules/`, `.github/instructions/`, etc.).
***
## Slash commands — Claude Code and Codex CLI
Two commands covering the tasks where LLM reasoning produces better results than a fixed script:
| Command | What it does |
| ------------ | ----------------------------------------------------------------------------------------------------- |
| `/rqb` | Creates specs, enriches expected responses, and builds/runs pipelines — routes based on your argument |
| `/rqb-debug` | Diagnoses failing endpoints and pipelines with contextual interpretation of each error |
***
## MCP server — MCP-compatible agents
Ten tools that return structured JSON or surgical context for the agent to act on programmatically:
| Tool | When to use |
| ---------------- | ----------------------------------------------------------------------------------------------- |
| `rqb_exec` | Execute a spec and get a structured result with diff |
| `rqb_diagnose` | Diagnose a failed endpoint with likely cause, next action, inspect targets, and verify commands |
| `rqb_flow` | Run a pipeline and get per-step state |
| `rqb_author` | Write a spec with validation guard and overwrite protection |
| `rqb_vars` | Check variable resolution before exec |
| `rqb_search` | Find specs by method, path, or tag |
| `rqb_context` | Build surgical or schema API context for a target, flow, or changed specs |
| `rqb_history` | Check execution trend over recent runs |
| `rqb_session` | Set env and vars once for all subsequent calls |
| `rqb_exec_batch` | Run multiple specs and get a summary table |
Spec and pipeline tools resolve variables the same way as the CLI: `_shared/env.md`, `.env.local`, `RQB_*` / `MAD_*`, session vars, then explicit tool `vars`.
***
## Recommended Claude Code setup
```bash theme={null}
rqb skills install --agent=claude-code
```
```bash theme={null}
rqb install mcp --agent=claude-code
```
```bash theme={null}
rqb serve
```
Keep the preview open while the agent edits specs — review and run changed files immediately in the browser.
With all three active:
* The agent knows Reqbook conventions and makes good decisions without prompting (skill)
* You can trigger complex workflows precisely without writing long prompts (slash commands)
* The agent gets structured results without parsing terminal output (MCP)
For implement, review, or debug runs, ask the agent to call `rqb_context` first with `mode: "surgical"`, `brief: true`, `max_fields: 12`, `include: "variables,request,response,errors,rules,verify"`, and an explicit `intent` such as `"implement"` or `"debug"`. Use `max_fields: 6` only for a known narrow lookup. If `rqb_exec` fails, call `rqb_diagnose` before reading backend source. This keeps the loop focused on the bounded contract, literal error codes, compact business rules, likely cause, inspect targets, and verify commands.
***
## Supported agents
| Agent | Skills | Slash commands | MCP |
| -------------- | ------ | -------------- | --- |
| Claude Code | ✓ | ✓ (2 commands) | ✓ |
| Codex CLI | ✓ | ✓ (2 commands) | ✓ |
| Cursor | ✓ | | ✓ |
| GitHub Copilot | ✓ | | ✓ |
| Antigravity | ✓ | | ✓ |
| OpenCode | ✓ | | ✓ |
| Windsurf | ✓ | | ✓ |
***
## Next steps
Install the skill, slash commands, and MCP in one command.
Full details on /rqb and /rqb-debug.
All 9 tools with input/output schemas and examples.