What is add-browser-tool?

A development guide for adding new browser operations to BrowserMesh, a system that exposes browser control through tools. It covers the shared interfaces, Playwright implementation, session routing, and tests.

Adding, extending, or renaming browser tools in BrowserMesh, including changes to its browser engine interface and Playwright adapter.

It helps prevent browser features from bypassing the system's rules for separate sessions, pages, operation tracking, and queued access.

How scrollDynasty/BrowserMesh configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to scrollDynasty/BrowserMesh. 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/scrollDynasty/BrowserMesh/master/.claude/skills/add-browser-tool/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/scrollDynasty/BrowserMesh

Made for: Claude Code.

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/scrolldynasty/browsermesh/add-browser-tool/github.svg)](https://agentmods.dev/skills/scrolldynasty/browsermesh/add-browser-tool)

Your own site

<a href="https://agentmods.dev/skills/scrolldynasty/browsermesh/add-browser-tool"><img src="https://agentmods.dev/badge/skills/scrolldynasty/browsermesh/add-browser-tool/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/scrolldynasty/browsermesh/add-browser-tool"><img src="https://agentmods.dev/badge/skills/scrolldynasty/browsermesh/add-browser-tool.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 919 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	$0.00069	$0.00919
Opus 5.5	$0.00028	$0.00368
Sonnet 5.5	$0.00014	$0.00184
Haiku 4.5	$0.00007	$0.00092

Measured 2mo ago against content hash 8ded4cc0f824, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

add-browser-tool 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.

.claude/skills/add-browser-tool/SKILL.md · 76 lines

How it starts

The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Adding a browser operation

Dependency direction is the whole point: define the contract first, implement it at the edge last. A capability that shows up in the MCP adapter before it exists in the port has already broken the architecture test.

Order of work

Define the engine-independent contract. Input and result types in src/domain/. No Playwright types, no MCP types.
Extend BrowserEnginePort (src/application/ports/browser-engine.ts) only if genuinely new engine capability is required. Reuse an existing method where the difference is routing.
Implement the concrete behaviour in src/adapters/playwright/playwright-browser-engine.ts. This is the only place that resolves handles into real Browser, BrowserContext, Page, or locators.
Route through BrowserMeshRuntime (src/runtime/browsermesh-runtime.ts).
Target an explicit sessionId. No implicit current session.
Target an explicit pageId for page-scoped operations. Reject a pageId owned by another session.
Pass live browser access through the session queue (src/runtime/serial-queue.ts) — read operations included.
Allocate and correlate an operationId.
Map concrete failures into stable BrowserMeshError codes (src/domain/errors.ts). Raw Playwright errors must never reach a client.
Expose it through validated MCP input in src/adapters/mcp/contracts.ts and register it in src/adapters/mcp/server.ts.
Write an AI-facing description — see the rules in CLAUDE.md; a description is chosen by a model, not read by a human.
Add positive and negative tests.
Add isolation, concurrency, and cleanup coverage where the operation touches live state.
Run the affected suites, then npm run verify.

What the compiler and tests will force

These are not optional; skipping one turns into a red suite rather than a silent omission.

ToolName is keyof typeof outputSchemas (contracts.ts:365). Adding an output schema creates the name.
toolPresentation is Record<ToolName, ToolPresentation> (contracts.ts:388), so TypeScript requires a title and annotations for the new tool.
tests/unit/tool-profiles.test.ts asserts every ToolName belongs to exactly one profile in src/adapters/mcp/tool-profiles.ts (core, observability, or persistence). A new tool that is in no profile fails here.
tests/integration/mcp.test.ts asserts discovered tool names equal Object.keys(outputSchemas) exactly, invokes every public tool, and validates its structuredContent.
tests/unit/architecture.test.ts rejects Playwright or MCP imports reaching domain, application, or runtime.

Read the full file on GitHub · 76 lines

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 · 76 lines · 69 tokens per session scan A 8ded4cc0f824

Subscribe to this mod's changes

add-browser-tool is a skill published in the GitHub repository scrollDynasty/BrowserMesh (3 stars, last pushed 2d ago), licensed Apache-2.0. It adds 69 tokens to every session and 919 once invoked, about $0.0003 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.

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