Instructions for building a desktop extension package for a Node.js server that provides London transport data. MCPB is the packaged extension format used for testing with Claude Desktop.

Use them to build the `.mcpb` file, check the build result, and install the extension in Claude Desktop.

They define the commands needed to install dependencies, compile the server, and create the extension bundle. This avoids having to work out the packaging process manually.

How oneill9/tfl-mcp-server configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to oneill9/tfl-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/oneill9/tfl-mcp-server/main/.agents/skills/build-mcpb/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/oneill9/tfl-mcp-server

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/oneill9/tfl-mcp-server/build-mcpb/github.svg)](https://agentmods.dev/skills/oneill9/tfl-mcp-server/build-mcpb)

Your own site

<a href="https://agentmods.dev/skills/oneill9/tfl-mcp-server/build-mcpb"><img src="https://agentmods.dev/badge/skills/oneill9/tfl-mcp-server/build-mcpb/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/oneill9/tfl-mcp-server/build-mcpb"><img src="https://agentmods.dev/badge/skills/oneill9/tfl-mcp-server/build-mcpb.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 168 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.

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	$0.00018	$0.00168
Opus 5.5	$0.00007	$0.00067
Sonnet 5.5	$0.00004	$0.00034
Haiku 4.5	$0.00002	$0.00017

Measured 2mo ago against content hash 873427c1344f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

build-mcpb 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.

.agents/skills/build-mcpb/SKILL.md · 16 lines

What it actually says

Build the MCPB extension bundle for the Node.js TfL MCP server.

Steps

Run the build script — execute bash scripts/build-mcpb.sh from the project root. This will:
- Install Node.js dependencies (npm ci)
- Compile TypeScript (npm run build)
- Pack the extension into build/tfl-mcp-server.mcpb using mcpb pack
Report the result — tell the user the path to the built .mcpb file and remind them they can install it with mcpb install build/tfl-mcp-server.mcpb or double-click it to open in Claude Desktop.

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.

2mo ago First seen · 16 lines · 18 tokens per session scan A 873427c1344f

Subscribe to this mod's changes

build-mcpb is a skill published in the GitHub repository oneill9/tfl-mcp-server (1 stars, last pushed 3d ago), licensed MIT. It adds 18 tokens to every session and 168 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 2026-08-31.

Building agents

build-mcpb next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
build-mcpboneill9/tfl-mcp-server	Skill	1	3d ago	MIT	A	18	Claude Code, Codex
imagegenopenai/codex	Skill	133k	yesterday	Apache-2.0	A	113	Codex
playwright-climicrosoft/playwright	Skill	99k	yesterday	Apache-2.0	A	19	Claude Code
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	79k	4d ago	MIT	A	200	Claude Code, Codex
systematic-debuggingobra/superpowers	Skill	313k	3d ago	MIT	A	21	Claude Code
next-cache-components-adoptionvercel/next.js	Skill	143k	today	MIT	A	95	Claude Code
next-partial-prefetching-adoptionvercel/next.js	Skill	143k	today	MIT	A	103	Claude Code

tfl-mcp-server: Skill for Claude Code