Borrowing it
Nothing to install: this file belongs to alexd73/PlanfixMCP. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/alexd73/PlanfixMCP/main/.opencode/skills/api-and-interface-design/SKILL.mdgit clone --depth 1 https://github.com/alexd73/PlanfixMCPWrote 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.
[](https://agentmods.dev/skills/alexd73/planfixmcp/api-and-interface-design)<a href="https://agentmods.dev/skills/alexd73/planfixmcp/api-and-interface-design"><img src="https://agentmods.dev/badge/skills/alexd73/planfixmcp/api-and-interface-design/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.
<a href="https://agentmods.dev/skills/alexd73/planfixmcp/api-and-interface-design"><img src="https://agentmods.dev/badge/skills/alexd73/planfixmcp/api-and-interface-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00049 | $0.02277 |
| Opus 5.5 | $0.00020 | $0.00911 |
| Sonnet 5.5 | $0.00010 | $0.00455 |
| Haiku 4.5 | $0.00005 | $0.00228 |
Grade A, and why
api-and-interface-design 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 2mo ago.
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.
The source is not reproduced here
No licence file
A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.
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.
- 2mo ago First seen · 295 lines · 49 tokens per session scan A 293db2903b41
api-and-interface-design is a skill published in the GitHub repository alexd73/PlanfixMCP (0 stars, last pushed 2mo ago), with no licence file. It adds 49 tokens to every session and 2,277 once invoked, about $0.0002 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 2026-08-31.
Other skills, from other repositories
browserwing-executor
Control browser automation through HTTP API. Supports page navigation, element interaction (click, type, select), data extraction, accessibility snapshot analysis, screenshot, JavaScript execution, and batch operations.
dstack-prototyping
Use with the dstack skill for model-serving work when the image, serving command, resources, backend/fleet choice, or service behavior is not proven. Guides task-first prototyping on real hardware, choosing fleets/backends that can reuse idle instances and caches, checking vLLM/SGLang sources, and verifying the final…
ranui
Build or modify products using ranui web components or ranui/builder. Resolve the installed component APIs, theme tokens, form behavior and lifecycle contracts before implementation.
sequence-diagrams
Create animated sequence diagrams showing interactions between participants using the Excalimate MCP server. Use when asked to visualize API call sequences, message flows, protocol handshakes, request/response patterns, authentication flows, or communication between services, users, and systems.
form-list-layout
Configure what a form and a list look like — sysuiform, sysuisection and sysuielement for forms; sysuilist, sysuilistelement and sysuirelatedlist for lists; sysfilter for saved filters. Views, why a field must exist in the dictionary first, and what snowcreatemenu really writes.
spine-design
Produce a system design doc — components, data flow, decisions made, tradeoffs, failure modes. Not a list of options. An actual design with calls made. Use when asked for "system design for", "architect this", "how should we build", or "design the backend".