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Steel MCP サーバー

鍛冶屋のバッジ

https://github.com/user-attachments/assets/25848033-40ea-4fa4-96f9-83b6153a0212

ClaudeのようなLLMがPuppeteerベースのツールやSteelを使ってWebをナビゲートできるようにする、モデルコンテキストプロトコル(MCP)サーバーです。Web Voyagerフレームワークをベースに、クリック、スクロール、入力など、あらゆる標準的なWeb操作やスクリーンショット撮影のためのツールを提供します。

次のようなタスクについて Claude に支援を依頼してください。

  • 「レシピを検索して材料リストを保存する」

  • 「荷物の配送状況を追跡する」

  • 「特定の商品の価格を検索して比較する」

  • 「オンライン求人応募フォームにご記入ください」

🚀 クイックスタート

以下は、Claude Desktop内でSteel Voyagerを実行するための簡潔なガイドです。環境オプションを調整するだけで、Steel Cloudとローカル/セルフホストインスタンスを切り替えることができます。

前提条件

  1. GitとNode.jsの最新バージョンがインストールされている

  2. クロードデスクトップがインストール済み

  3. (オプション) セルフホストを計画している場合、ローカルで実行されるSteel Docker イメージ

  4. (オプション)Steel Cloud をご利用の場合は、API キーをお持ちください。こちらから取得してください。


A) クイックスタート(Steel Cloud)

  1. プロジェクトをクローンしてビルドします。

    git clone https://github.com/steel-dev/steel-mcp-server.git
    cd steel-mcp-server
    npm install
    npm run build
  2. サーバー エントリを追加して、Claude Desktop ( ~/Library/Application Support/Claude/claude_desktop_config.json ) を構成します。

    {
      "mcpServers": {
        "steel-puppeteer": {
          "command": "node",
          "args": ["path/to/steel-voyager/dist/index.js"],
          "env": {
            "STEEL_LOCAL": "false",
            "STEEL_API_KEY": "YOUR_STEEL_API_KEY_HERE",
            "GLOBAL_WAIT_SECONDS": "1"
          }
        }
      }
    }
    • 「YOUR_STEEL_API_KEY_HERE」を有効な Steel API キーに置き換えます。

    • クラウド モードの場合は、「STEEL_LOCAL」が「false」に設定されていることを確認します。

  3. Claude Desktopを起動します。MCPサーバーがクラウドモードで自動的に起動します。

  4. (オプション)ダッシュボードでアクティブな Steel Browser セッションを表示または管理できます。


B) クイックスタート(ローカル / セルフホスト Steel)

  1. ローカルまたはセルフホスト型の Steel サービスが実行されていることを確認します (例: オープンソースの Steel Docker イメージを使用)。

  2. プロジェクトをクローンしてビルドします (まだ実行していない場合は上記と同じです)。

    git clone https://github.com/steel-dev/steel-mcp-server.git
    cd steel-mcp-server
    npm install
    npm run build
  3. Claude Desktop ( ~/Library/Application Support/Claude/claude_desktop_config.json ) をローカル モード用に構成します。

    {
      "mcpServers": {
        "steel-puppeteer": {
          "command": "node",
          "args": ["path/to/steel-voyager/dist/index.js"],
          "env": {
            "STEEL_LOCAL": "true",
            "STEEL_BASE_URL": "http://localhost:3000",
            "GLOBAL_WAIT_SECONDS": "1"
          }
        }
      }
    }
    • 「STEEL_LOCAL」は「true」でなければなりません。

    • クラウド サーバーで自己ホストする場合は、ローカル/自己ホスト Steel URL を指すように "STEEL_BASE_URL" を構成します。

  4. Claude Desktop を起動すると、ローカルで実行されている Steel に接続され、Steel Voyager がローカル モードで起動します。

  5. (オプション) セッションをローカルで表示するには、セルフホストダッシュボード ( localhost:5173 ) または Steel ランタイム環境に固有のログにアクセスします。


これで完了です。Claude Desktop が起動すると、MCP サーバーがバックグラウンドでオーケストレーションされ、Steel Voyager を通じて Web 自動化機能を操作できるようになります。

セットアップの詳細や問題がある場合は、MCP セットアップ ドキュメントをご覧ください: https://modelcontextprotocol.io/quickstart/user

Related MCP server: Puppeteer MCP Server

コンポーネント

ツール

  • ナビゲート

    • ブラウザで任意のURLに移動する

    • 入力:

  • 検索

  • クリック

    • 番号付きラベルを使用してページ上の要素をクリックします

    • 入力:

      • label (数値、必須): クリックする要素のラベル番号。

  • タイプ

    • 番号付きラベルを使用して入力フィールドにテキストを入力します

    • 入力:

      • label (数値、必須):入力フィールドのラベル番号。

      • text (文字列、必須): フィールドに入力するテキスト。

      • replaceText (ブール値、オプション): true の場合、フィールド内の既存のテキストを置き換えます。

  • スクロールダウン

    • ページを下にスクロールします

    • 入力:

      • pixels (整数、オプション):下にスクロールするピクセル数。指定しない場合は、1ページ分スクロールします。

  • スクロールアップ

    • ページを上にスクロール

    • 入力:

      • pixels (整数、オプション):上にスクロールするピクセル数。指定しない場合は、1ページ分スクロールします。

  • 戻る

    • ブラウザ履歴の前のページへ移動する

    • 入力は不要です

  • 待って

    • 最大 10 秒間待機します。これは、ページの読み込みが遅い場合や、動的なコンテンツの表示に時間がかかる場合に便利です。

    • 入力:

      • seconds (数値、必須): 待機する秒数 (0 ~ 10)。

  • マークされていないスクリーンショットを保存

    • 境界ボックスやハイライトなしで現在のページをキャプチャし、リソースとして保存します。

    • 入力:

      • resourceName (文字列、オプション): スクリーンショットを保存する名前(例:"before_login")。省略した場合は、汎用的な名前が自動的に生成されます。

リソース

  • スクリーンショット: 保存された各スクリーンショットは、次の形式の MCP リソース URI を介してアクセスできます: • screenshot://RESOURCE_NAME

    これらのスクリーンショットは、「save_unmarked_screenshot」ツールを指定した場合、またはアクション(ほとんどのツールの場合)で注釈付きスクリーンショットが作成された場合にサーバーに保存されます。これらの画像は、標準のMCPリソース取得リクエストを通じて取得できます。

(注: コンソール ログは分析とデバッグのために引き続き収集されますが、この実装では取得可能なリソースとして公開されません。コンソール ログはサーバーのログに表示されますが、MCP リソース URI 経由では提供されません。)

主な特徴

  • Puppeteerによるブラウザ自動化

  • ブラウザセッション管理のためのSteel統合

  • 番号付きラベルによる視覚的な要素識別

  • スクリーンショット機能

  • 基本的なウェブインタラクション(ナビゲーション、クリック、フォームの入力)

  • スクロールによる遅延読み込みのサポート

  • ローカルおよびリモートの Steel インスタンスのサポート

境界ボックスの理解

ページを操作する際、Steel Puppeteer はインタラクティブな要素を識別するのに役立つ視覚的なオーバーレイを追加します。

  • 各インタラクティブ要素(ボタン、リンク、入力)には固有の番号付きラベルが付けられます

  • 色付きのボックスが要素の境界を示します

  • ラベルは要素の上または内部に表示されるので、簡単に参照できます。

  • クリックまたは入力操作の要素を指定するときにこれらの番号を使用します

構成

Steel Voyagerは「ローカル」と「クラウド」の2つのモードで実行できます。この動作は環境変数によって制御されます。以下に概要を示します。

環境変数

デフォルト

説明

スチール_ローカル

"間違い"

Steel Voyager がローカル (true) モードで実行されるか、クラウド (false) モードで実行されるかを決定します。

STEEL_API_KEY

(なし)

STEEL_LOCAL = "false" の場合にのみ必要です。Steelエンドポイントへのリクエストの認証に使用されます。

スチールベースURL

「 https://api.steel.dev 」

Steel APIのベースURL。Steelサーバーをローカルまたは独自のクラウド環境でセルフホストする場合は、このURLをオーバーライドしてください。STEEL_LOCAL = "true" かつ STEEL_BASE_URL が設定されていない場合、デフォルトは " http://localhost:3000 " になります。

グローバル_待機秒数

(なし)

オプション。各ツールアクションの後に待機する秒数(たとえば、読み込みが遅いページを許可する場合)。

ローカルモード

  1. STEEL_LOCAL="true" を設定します。

  2. (オプション)カスタムドメインでホストしている場合は、Steelサーバーを指すようにSTEEL_BASE_URLを設定します。それ以外の場合、Steel Voyagerはデフォルトでhttp://localhost:3000を使用します。

  3. このモードでは API キーは必要ありません。

  4. Puppeteerはws://0.0.0.0:3000経由で接続します。

例:

エクスポート STEEL_LOCAL="true"

export STEEL_BASE_URL=" http://localhost:3000 " # 上書きする場合のみ

クラウドモード

  1. STEEL_LOCAL="false" を設定します。

  2. STEEL_API_KEY を設定して、Steel Voyager が Steel クラウド サービス (または STEEL_BASE_URL を変更した場合はセルフホスト型 Steel) で認証できるようにします。

  3. STEEL_BASE_URL のデフォルトはhttps://api.steel.devです。別のエンドポイントで自己ホスト型 Steel インスタンスを実行している場合は、これを上書きします。

  4. Puppeteer は wss://connect.steel.dev?sessionId=…&apiKey=… 経由で接続します。

例:

エクスポート STEEL_LOCAL="false"

エクスポート STEEL_API_KEY="YOUR_STEEL_API_KEY_HERE"

クロードデスクトップ構成

Steel Voyager を Claude Desktop で使用するには、次のような内容を構成ファイル (通常は ~/Library/Application Support/Claude/claude_desktop_config.json にあります) に追加します。

{
  "mcpServers": {
    "steel-puppeteer": {
      "command": "node",
      "args": ["path/to/steel-puppeteer/dist/index.js"],
      "env": {
        "STEEL_LOCAL": "false",
        "STEEL_API_KEY": "your_api_key_here"
      }
    }
  }
}

希望するモードに合わせて環境変数を調整します。

• ローカル/自己ホストで実行している場合は、 "STEEL_LOCAL": "true"を維持し、オプションで"STEEL_BASE_URL": "http://localhost:3000"維持します。
• クラウド モードで実行している場合は、 "STEEL_LOCAL": "true"を削除し、 "STEEL_LOCAL": "false"を追加して、 "STEEL_API_KEY": "<YourKey>"を指定します。これにより、Claude Desktop は Steel Voyager を正しいモードで起動できるようになります。

インストールと実行

Smithery経由でインストール

Smithery経由で Claude Desktop 用の Steel MCP Server を自動的にインストールするには:

npx -y @smithery/cli install @steel-dev/steel-mcp-server --client claude

地域開発

  1. リポジトリをクローンする

  2. 依存関係をインストールします:

    npm install
  3. プロジェクトをビルドします。

    npm run build
  4. サーバーを起動します。

    npm start

使用例 📹

私たちはクロードに、その新しい能力で私たちを感動させるように頼みました。そして、クロードはソラの最新の開発を研究し、モデルの背後にあるデータとその仕組みを示すインタラクティブな視覚化を作成することにしました🤯

https://github.com/user-attachments/assets/8d4293ea-03fc-459f-ba6b-291f5b017ad7

*画質が悪くてすみません。github ではビデオを 10 MB 未満に保つように強制されているので :/

トラブルシューティング

よくある問題と解決策:

  1. クラウドサービスをご利用の際は、Steel APIキーを確認し、ローカルのSteelインスタンスが稼働していることを確認してください。また、サービスへの適切なネットワーク接続もご確認ください。

  2. ページがレンダリングまたはマークアップされて claude に送信される方法に問題がある場合は、 GLOBAL_WAIT_SECONDS環境変数を使用して構成に遅延を追加してみてください。

  3. ページが完全に読み込まれていることを確認し、ビューポートのサイズ設定を確認してください。スクリーンショットをキャプチャするのに十分なメモリがシステムに確保されていることを確認してください。

  4. セッションのクリーンアップは現時点では最適ではないため、タスクを実行するためにセッションが起動されたときに手動でセッションを解放する必要がある場合があります。

  5. 正しい方法で claude に指示を与えると、パフォーマンスの向上や、発生する可能性のある愚かなミスの回避に大いに役立ちます。

  6. セッション ビューアーを活用して、モデルがストップアウトされる可能性のある場所を分析します。

  7. ブラウザ操作が15~20回ほど続くと、Claudeのコンテキストウィンドウが画像で埋め尽くされ、動作が遅くなり始めます。それほどひどい状況ではないはずですが、特にClaudeデスクトップクライアントの遅延が顕著で、若干の遅延が発生しています。

貢献

このプロジェクトは実験段階であり、現在活発に開発中です。皆様からの貢献を歓迎いたします。

  1. リポジトリをフォークする

  2. 機能ブランチを作成する

  3. プルリクエストを送信する

以下を含めてください:

  • 変更の明確な説明

  • モチベーション

  • ドキュメントの更新

免責事項

⚠️ このプロジェクトは実験的なものであり、Web Voyager のコードベースに基づいています。本番環境での使用は自己責任でお願いします。

Available Tools

16 tools
steel_actInteract with the pageA
Destructive

Click, type, fill a form, select an option, hover, scroll, press a key, go back, or dismiss a cookie or consent overlay. Target elements by the @eN reference from steel_snapshot or steel_find, or by a CSS selector. Always reports what actually changed, and says so plainly when nothing did.

ParametersJSON Schema
NameRequiredDescriptionDefault
valueNoText to type, option to select, key name to press, or scroll distance in pixels.
actionYesWhat to do.
fieldsNoFor fill_form: the fields to fill, in order, in one round trip.
targetNoA @eN reference or a CSS selector. Not needed for scroll, press, go_back or dismiss_overlays.
max_tokensNoCap on the text returned, in tokens. Defaults to 8000.
session_idYesLive session_id from steel_session_create.
include_snapshotNoAlso return the page structure afterwards. Off by default.

TDQS

A4.2/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already provide destructiveHint=true and openWorldHint=true, so the mutation risk is flagged. The description adds value beyond that by promising that the tool always reports what actually changed and says so plainly when nothing did, and by enumerating the side-effecting actions it performs. This is useful behavioral context rather than a contradiction.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three tight sentences cover the action set, targeting strategy, and output reporting behavior. Every sentence earns its place; there is no filler or repetition of schema details.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 7-parameter, 10-action tool with no output schema, the description covers the action set, target syntax, and reporting promise. Operational details like session_id and max_tokens are handled by the schema. The return format is only vaguely described, but the honesty guarantee compensates enough for a tool of this complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so every parameter is already documented in the schema. The description adds only light enrichment, such as mentioning @eN references from steel_snapshot/steel_find and cookie/consent overlays. Since the schema carries the parameter burden, a baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a concrete set of interactions—click, type, fill a form, select, hover, scroll, press, go back, dismiss overlays—and ties them to a specific resource: the current page. It also distinguishes itself from siblings like steel_navigate and steel_snapshot by making clear this is the general page-interaction tool.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear usage context: target elements by @eN references from steel_snapshot or steel_find, or by CSS selector. This implies the prerequisite of running snapshot/find first and orients the agent to the correct workflow. It does not explicitly state when not to use the tool or name alternatives, but the usage situation is still clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_batchRun several browser steps at onceA
Destructive

Run known reversible steps whose later targets need no fresh read. Stops on failure or login/challenge; hand off the same session and resume only unrun steps. Stop before payment/final confirmation.

ParametersJSON Schema
NameRequiredDescriptionDefault
stepsYesSteps to run in order.
max_tokensNoCap on the text returned, in tokens. Defaults to 8000.
session_idYesLive session_id from steel_session_create.
include_snapshotNoReturn the page structure once, after the last step.

TDQS

A4/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare destructiveHint and openWorldHint, but the description goes further by disclosing that execution stops on failure or login/challenge, the session is handed off, and only unrun steps should be resumed. It also warns against including payment or final confirmation steps. This adds meaningful behavioral context beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is three sentences with no wasted words. The first sentence front-loads the core usage condition, the second explains failure behavior, and the third gives a safety boundary. Every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a batch tool with no output schema, the description covers the essential selection criteria, failure behavior, and safety constraints. It does not describe the return shape or how results from completed steps are surfaced, which is a minor gap, but the critical invocation decisions are well supported.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents the session_id, steps, max_tokens, and include_snapshot parameters. The description does not add parameter-specific syntax or format details, which is acceptable given full schema coverage. It provides general behavioral guidance but not deeper parameter semantics.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool runs multiple known reversible browser steps as a batch, which distinguishes it from the single-step sibling tools like steel_navigate, steel_act, and steel_wait_for. The title reinforces this by saying 'Run several browser steps at once.' It does not name a sibling explicitly, but the scope and specificity are strong enough to identify the tool's purpose.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides a concrete inclusion criterion: use for known reversible steps whose later targets do not need a fresh read. It also gives exclusions by warning to stop before payment/final confirmation and noting the batch stops on login/challenge. It does not explicitly name an alternative tool, so it falls just short of fully explicit routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_findFind an element on the pageA
Read-only

Find labelled elements by text, safe regex or role and return their @eN refs.

ParametersJSON Schema
NameRequiredDescriptionDefault
roleNoOnly return elements with this role, e.g. button or link.
textNoCase-insensitive substring of the element label.
regexNoSafe regular expression matched against the element label.
cursorNoCursor from a previous truncated response, to continue reading where it stopped.
max_tokensNoCap on the text returned, in tokens. Defaults to 8000.
session_idYesLive session_id from steel_session_create.
max_resultsNoCap on matches returned.
interactive_onlyNoOnly return elements that can actually be clicked or typed into.

TDQS

A3.8/5.0
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare read-only and open-world behavior. The description adds useful context by noting that only labelled elements are matched, that regex matching is safe, and that the result is @eN refs. It does not disclose truncation or cursor continuation behavior, but the schema covers those details and the safety profile is already established by annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence states the action, the matching methods, and the return type with no filler. Every phrase earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with eight parameters and no output schema, the description provides the essential return concept (@eN refs) and the matching criteria. Combined with the fully described schema and read-only annotations, this is nearly complete; only explicit sibling differentiation and pagination caveats are missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3 because the schema already documents all eight parameters. The description adds a high-level grouping of search modes (text, regex, role) but no new semantic detail beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Find'), a concrete resource ('labelled elements'), and explicit search criteria (text, safe regex, role), plus the return type (@eN refs). This clearly differentiates it from sibling tools like steel_snapshot or steel_scrape, which retrieve page content rather than locate specific elements.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The intended use is reasonably clear: call this when you need element references by label. However, it never explicitly states when to prefer it over alternatives such as steel_snapshot or steel_wait_for, nor does it provide any exclusions. Usage is implied rather than directly guided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_navigateOpen a URL in a browser sessionA
Destructive

Navigate a live session and wait for it to settle. Reports the final URL and changes; set include_snapshot to also read the page.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlYesWhere to go.
max_tokensNoCap on the text returned, in tokens. Defaults to 8000.
session_idYesLive session_id from steel_session_create.
include_snapshotNoAlso return the accessibility snapshot. Off by default because it is expensive.

TDQS

A3.9/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond annotations, the description discloses that the tool waits for the page to settle, reports the final URL and changes, and that the snapshot is off by default because it is expensive. These are meaningful behavioral details. It does not contradict the openWorldHint or destructiveHint annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two concise sentences front-load the core behavior and then add the key option. Every clause earns its place with no repetition of schema details.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a navigation tool with no output schema, the description covers the main behavioral contract: navigating, waiting, reporting URL and changes, and the snapshot option. It does not fully describe the shape of the returned changes, but with annotations covering safety and 100% parameter schema coverage, the gaps are acceptable.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3. The description adds value by explaining include_snapshot ('also read the page', 'expensive') and by clarifying what navigation returns ('reports the final URL and changes'), which gives context to the url and session_id parameters.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action: 'Navigate a live session and wait for it to settle.' The title 'Open a URL in a browser session' reinforces the resource and action. It does not explicitly compare against sibling tools like steel_scrape or steel_act, so it misses full differentiation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies when to use it: to navigate a live session and wait for it to settle, with include_snapshot when page content is needed. However, it offers no explicit exclusions or alternatives among siblings, such as 'use steel_scrape for extraction' or 'use steel_act for actions.'

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_pdfRender a web page as PDFA
Read-onlyIdempotent

Render a page to PDF and return a link to the file. Starts no browser session. Use steel_scrape if you want to read the text — the PDF link is for handing a document to a person.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlYesThe page to render.
delay_msNoWait this long after load.
use_proxyNoUse a Steel residential proxy.

TDQS

A4.5/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the read-only, idempotent, and open-world annotations, the description adds two useful behaviors: it starts no browser session and it returns a link rather than inline content. It does not contradict the annotations, so credit is given for the extra context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two succinct sentences front-load the core purpose and return format, then give the alternative and use case. There is no filler or repetition; every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple three-parameter tool with a full schema and safety annotations, the description covers purpose, return format, session behavior, and the key sibling alternative. No output schema exists, but the description explicitly states the return value, so nothing essential is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already explains url, delay_ms, and use_proxy. The description adds no parameter-level detail, but the baseline of 3 applies because the schema carries the full burden and the description doesn't need to compensate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific verb ('Render') and resource ('a page to PDF') and states the deliverable ('return a link to the file'). It also distinguishes itself from steel_scrape by noting the PDF is for handing a document to a person, so an agent can tell it apart from the most similar sibling.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly routes the agent: use steel_scrape when the goal is to read the text, and use steel_pdf when the goal is to produce a document for a person. This is clear when-to-use guidance with a named alternative, leaving little to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_scrapeRead a web pageA
Read-onlyIdempotent

Read a web page as markdown or HTML through a real browser, so JavaScript-rendered pages and sites that block plain HTTP fetches still work. Starts no browser session, so there is nothing to release afterwards. Always returns the page links and metadata alongside the content. Use this first for anything you only need to read; reach for steel_session_create only when you need to click, type or move through several pages.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlYesThe page to read.
cursorNoCursor from a previous truncated response, to continue reading where it stopped.
formatNoFormats to return. Each extra format repeats the page inside the shared budget.
delay_msNoWait this long after load.
use_proxyNoRoute through a Steel-managed residential proxy. Needs a verified paid balance.
max_tokensNoCap on the text returned, in tokens. Defaults to 8000.

TDQS

A4.4/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, and the description contradicts none of them. Beyond that, it adds three substantive behavioral facts: the tool runs a real browser so JS rendering works, it starts no browser session so there is nothing to release, and it always returns page links and metadata alongside content. This is solid context beyond the annotations, though it stops short of disclosing failure behavior or rate limits.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Four sentences with zero waste: purpose and capability, session lifecycle, return-value behavior, and usage routing each get one sentence. The core action is front-loaded in the first line, and every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with one required parameter, a fully covered schema, and rich annotations, the description covers selection criteria, session handling, and return basics. Since there is no output schema, the return structure is only sketched as 'links and metadata,' but the combination of a 100%-covered schema, strong annotations, and this description leaves no critical gap for correct selection and invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all six parameters are already fully documented in the schema. The description adds only marginal parameter-level meaning (markdown/HTML correspond to the format parameter, and 'no browser session' explains why no session parameter exists). Baseline 3 is appropriate since the schema does the heavy lifting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific action — 'Read a web page as markdown or HTML through a real browser' — and adds distinguishing capability detail: it handles JavaScript-rendered pages and sites that block plain HTTP fetches. An agent can clearly tell this apart from steel_screenshot, steel_pdf, and steel_session_create without opening their schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The last sentence is an explicit routing directive: 'Use this first for anything you only need to read; reach for steel_session_create only when you need to click, type or move through several pages.' It names the alternative tool and the exact condition that selects it, leaving nothing to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_screenshotScreenshot a web pageA
Read-onlyIdempotent

Capture a page image. URL captures are user-facing PNG artifacts; session captures are model-visible JPEG evidence. Pixels are not action targets, so use steel_snapshot to click or type.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlNoPage to capture. Starts no browser session.
inlineNoFor URL captures only: false returns just a link. Defaults to true.
full_pageNoCapture the whole scrollable page, not just the viewport.
use_proxyNoUse a Steel residential proxy for a URL capture.
session_idNoCapture the current page of this session instead. Returns the image inline.

TDQS

A4.6/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered. The description adds behavioral context beyond annotations: output artifact formats (PNG vs JPEG) and the non-interactive nature of pixels. It does not contradict the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two tight sentences with no filler. The core action is front-loaded, artifact distinctions follow, and the sibling-routing caveat is placed last. Every sentence earns its place and nothing repeats schema content.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With 100% schema coverage and read-only/idempotent annotations, the description covers the key disambiguation from steel_snapshot and the two capture modes. It does not explain what happens when neither url nor session_id is provided, but the optional parameter schema and mode descriptions give sufficient guidance for a competent agent.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema descriptions cover all 5 parameters, so the baseline is 3. The description adds mode-level meaning that helps select between url and session_id by specifying output format and audience. It does not re-explain full_page or use_proxy, but those are already well documented in the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource: 'Capture a page image.' It further distinguishes URL captures and session captures by artifact type, and differentiates the tool from steel_snapshot by noting that pixels are not action targets. This makes the tool's purpose unambiguous relative to siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly tells agents when not to use this tool: 'Pixels are not action targets, so use steel_snapshot to click or type.' It also provides mode-selection guidance by contrasting user-facing PNG URL captures with model-visible JPEG session captures. This gives clear routing versus the main sibling alternative.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_session_createStart sessionC
Destructive

Billed; profiles/credentials via session_options; release.

ParametersJSON Schema
NameRequiredDescriptionDefault
guestNoFresh browser; skip profiles.
deviceNoClass.
viewportNoPixels.
block_adsNoAds.
namespaceNoName; not secret.
use_proxyNoProxy.
profile_idNoUUID; not secret.
timeout_msNoLifetime ms.
configurationNoPlan token.
solve_captchaNoCAPTCHA.

TDQS

C2.8/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With only openWorldHint/destructiveHint annotations, the description adds meaningful behavioral context: the operation is billed, and the created session must be released, which suggests a chargeable, long-lived resource. It doesn't go into consequences, but it reveals cost and lifecycle beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness2/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The definition is extremely short, but it is under-specified rather than economically structured; the fragments are not front-loaded with the core purpose and read as disconnected warnings rather than a purposeful summary.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 10-parameter, billed, destructive-flagged creator with no output schema, the description omits crucial context: what the call returns (e.g., session id), how billing is triggered, what 'release' implies, and any setup prerequisites. The cost/lifecycle hints are useful but far from complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all 10 parameters. The prose description adds no parameter-level detail; 'profiles/credentials via session_options' is a routing hint, not semantics for any specific parameter. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose2/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description never states the core action; it is a fragment list ('Billed; profiles/credentials via session_options; release.') that forces the agent to infer 'create session' from the name/title. It also doesn't differentiate this creator from siblings like steel_session_live_view beyond the title.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The fragments imply some usage boundaries: credentials/profiles should go through steel_session_options, and the caller should later release the session. However, there is no explicit when-to-use, prerequisites, or exclusion guidance for the other sibling tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_session_diagnosticsExplain what a browser session didA
Read-onlyIdempotent

Read live/released activity or list live handles; never starts a browser.

ParametersJSON Schema
NameRequiredDescriptionDefault
sinceNoOnly events at or after this ISO-8601 time.
cursorNoCursor from a previous truncated response, to continue reading where it stopped.
list_liveNoList this credential's recoverable live session handles.
max_tokensNoCap on the text returned, in tokens. Defaults to 8000.
session_idNoLive id from steel_session_create.
steel_session_idNoFinished Steel dashboard UUID.

TDQS

A4.2/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint and idempotentHint, and the description reinforces safety with 'Read' and 'never starts a browser.' It adds a useful behavioral boundary that is not fully captured by the annotations alone: no browser is launched during invocation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

One short sentence delivers the core action, the scope, and a key exclusion. Every word earns its place, and the most important behavior is front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only diagnostics tool with no required parameters, the description plus annotations provide enough context for selection and safe invocation. A bit more detail about what 'activity' includes or how output is returned would help, but the absence is not critical given the schema and annotations.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the parameters are fully documented there. The description's 'live/released activity' and 'list live handles' loosely map to session_id, steel_session_id, and list_live, but it adds no parameter-level detail beyond what the schema already provides.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific operation and resource: 'Read live/released activity or list live handles.' It also distinguishes itself from sibling tools by adding 'never starts a browser,' which separates it from session-creating or browser-acting tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description clearly indicates this tool is for reading diagnostics or listing live handles, not for launching a browser. However, it does not explicitly name siblings like steel_session_live_view or steel_session_replay, leaving some routing to the agent's inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_session_handoffHand the browser to a personA
Destructive

Pause for a person to take exclusive control of this same live browser, then resume only after hand-back. Use for sensitive input, local files, review, or any manual step.

ParametersJSON Schema
NameRequiredDescriptionDefault
reasonYesWhy a person needs control.
session_idYesLive session_id from steel_session_create.

TDQS

A4.5/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description adds behavior not visible in annotations: the tool pauses the current flow, grants exclusive human control, and resumes only after hand-back. This goes beyond the destructiveHint/openWorldHint annotations to explain the handoff lifecycle.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences with no filler; the core behavior is front-loaded and the usage guidance follows immediately. Every phrase earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter handoff tool with annotations covering safety, the description fully explains what happens, when to use it, and how the handoff is resolved. No output schema is needed because the behavior is the primary contract.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and already documents both parameters. The description still adds value by mapping the reason enum to concrete scenarios (sensitive input, local files, review, or any manual step), which helps an agent choose the correct value.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Description states a clear action—'Pause for a person to take exclusive control of this same live browser'—and the title reinforces the handoff behavior. It is easily distinguished from sibling session/automation tools, which all operate under agent control.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly lists when to use it: 'sensitive input, local files, review, or any manual step.' It doesn't explicitly state when not to use it or name alternatives, but the use-case list is sufficient guidance for an agent.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_session_live_viewLive view connectionC
Destructive

App-only viewer and control lease; no page content.

ParametersJSON Schema
NameRequiredDescriptionDefault
actionNo
session_idNoOmit to stream the newest live session this credential owns, which is what a viewer that never received the session does.
control_tokenNo

TDQS

C2.4/5.0
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare openWorldHint and destructiveHint, so the description does not need to restate those. It adds a little context with 'app-only' and 'no page content,' but it does not disclose the lease lifecycle, side effects of release, or what happens to a control lease across actions. There is no contradiction with the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness2/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is very short and contains no filler, but it is under-specified to the point of being a cryptic fragment. It front-loads no actionable instruction and leaves the agent to infer meaning from the title and schema, which is not effective conciseness.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a three-parameter control tool with no output schema, destructive and open-world annotations, and many related session siblings, this description is insufficient. The only substantive guidance comes from the session_id schema description; the agent still lacks action semantics, token requirements, and selection criteria.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is only 33%: only session_id has a description, while action and control_token are undocumented. The description's word 'lease' loosely relates to the action enum, but it does not explain connect, acquire, renew, or release semantics, nor does it clarify what control_token is or when it is needed.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose3/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description communicates that this tool is about an app-only viewer/control lease and explicitly notes 'no page content,' which gives some domain context. However, it is phrased as a noun fragment rather than a clear verb+resource statement, and it does not distinguish this tool from siblings like steel_session_create, steel_session_release, or steel_session_handoff.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description offers no guidance on when to use this tool versus its siblings. 'No page content' hints at an exclusion, but there are no explicit conditions, alternatives, or when-not-to-use signals, leaving an agent to guess whether live_view is appropriate relative to session_create, session_release, or handoff.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_session_optionsPlan sessionC
Read-only

Find profiles/credentials; plan setup.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlYesURL.
goalYesMode.
needsNoUnique;protected_text=read;captcha!=read/protected_text;persist_profile=account.
cursorNoCursor.
countryNolocation ISO.
minutesNolong_running min.

TDQS

C2.6/5.0
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds minimal behavioral context consistent with read-only behavior (finding profiles/credentials and planning), but it does not disclose what the plan contains, whether live network checks are performed, or what the output looks like. It does not contradict the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness2/5

Is the description appropriately sized, front-loaded, and free of redundancy?

At six words, the description is under-specified rather than genuinely concise. 'Find profiles/credentials; plan setup' reads like a note-to-self and fails to earn its place as a functional tool definition—there is no front-loaded verb-object statement of effect, no scope, and no return behavior.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with 6 parameters, no output schema, and complex inter-parameter constraints (needs enums with exclusion logic), this description is far too thin. An agent cannot determine what the tool returns, how the goal enum affects the plan, or how this differs from other session tools. The cryptic schema notes are not compensated for by the description.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline of 3 applies. The description itself adds nothing about parameters like needs, cursor, country, or minutes, and the schema's own descriptions are cryptic (e.g., goal is just 'Mode'; needs uses terse constraint strings like 'protected_text=read'), but per the rubric the high schema coverage keeps this at baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose3/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description offers a concrete verb+resource in 'Find profiles/credentials' but 'plan setup' is vague and largely restates the title 'Plan session.' It hints at a discovery/planning operation but never states what the tool actually returns or does with the found profiles/credentials, and it does not clearly distinguish itself from siblings like steel_session_create or steel_find.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no guidance on when to use this tool versus alternatives. It does not mention steel_session_create, steel_find, or any sibling, nor any condition such as 'call before creating a session.' An agent is left to infer the intended workflow entirely from the tool name and terse fragments.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_session_releaseRelease a browser sessionA
DestructiveIdempotent

Shut down the current browser and stop the meter. Safe to call twice. Its current URL and session-only page state are gone afterwards. A profile is saved only when persistence was requested. Read what you need first; this reports the final URL and title.

ParametersJSON Schema
NameRequiredDescriptionDefault
session_idYesLive session_id from steel_session_create.

TDQS

A4.3/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description adds substantial behavioral detail beyond the annotations: it reports idempotency ('Safe to call twice'), destructive effects ('current URL and session-only page state are gone'), persistence rules, and return value ('reports the final URL and title'). This fully discloses the side effects and consequences of calling the tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is concise, front-loaded with the primary action ('Shut down the current browser and stop the meter'), then covers safety, side effects, persistence, and return behavior in four short sentences. Every sentence adds meaningful information without redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a low-complexity tool with one parameter and no output schema, the description is complete: it covers the destructive nature, idempotency, persistence behavior, return value, and usage timing. Nothing needed for correct invocation or expectation-setting is omitted.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema already provides 100% coverage for the single parameter, including 'Live session_id from steel_session_create.' The description does not need to add parameter-level detail, and it does not. Baseline score of 3 is appropriate because the description adds no additional parameter semantics beyond what the schema already documents.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's function: 'Shut down the current browser and stop the meter.' This is a specific verb + resource combination that makes the core purpose obvious. It does not explicitly name sibling tools for differentiation, but the terminating nature is distinct enough from the listed siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear usage context: 'Read what you need first' signals that this should be called after data extraction is complete. It also notes the persistence caveat ('A profile is saved only when persistence was requested'), which informs the user whether they can expect preserved state. It does not explicitly contrast with alternatives like handoff or replay, but the when-to-use guidance is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_session_replayOpen a finished sessionA
Read-onlyIdempotent

Call only when the user explicitly asks to watch or replay a finished session. Returns its Steel dashboard link without starting a browser; use steel_session_diagnostics to inspect or explain activity.

ParametersJSON Schema
NameRequiredDescriptionDefault
steel_session_idNoFinished Steel UUID; omit for latest released.

TDQS

A4.7/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already carry the safety profile (readOnlyHint, idempotentHint, openWorldHint), so the bar is lower, and the description adds genuinely valuable behavioral context beyond them: it clarifies the tool returns a dashboard link and does NOT start a browser, correcting the natural but wrong assumption that 'replay' spawns a browser session. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, zero fluff, and the most decision-critical information (usage condition) is front-loaded. Every clause earns its place: the trigger, the behavioral clarification, the return value, and the sibling routing.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool of this complexity — one optional parameter, full schema coverage, strong annotations, simple return value — nothing an agent needs is missing. It covers when to call, what happens (no browser), what comes back (dashboard link), and where to go for the related task, despite having no output schema to lean on.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the parameter (steel_session_id with UUID pattern and 'Finished Steel UUID; omit for latest released') is fully documented in the schema. The description adds no parameter-level detail, which is appropriate — baseline 3 applies when the schema does the heavy lifting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('watch or replay a finished session') and a concrete outcome ('Returns its Steel dashboard link without starting a browser'). Explicitly differentiates from sibling steel_session_diagnostics, and the contrast with steel_session_live_view (finished vs. live) is evident from context.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit, restrictive trigger ('Call only when the user explicitly asks to watch or replay a finished session') and names the alternative tool for the neighboring case ('use steel_session_diagnostics to inspect or explain activity'). An agent needs zero inference to decide when to invoke this.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_snapshotRead the page structureA
Read-only

Return the page as a compact accessibility tree with a @eN reference on every element you can click or type into. This is the read to use before acting. Elements with no reference cannot be targeted. If you already know what you are looking for, steel_find is much cheaper.

ParametersJSON Schema
NameRequiredDescriptionDefault
cursorNoCursor from a previous truncated response, to continue reading where it stopped.
max_tokensNoCap on the text returned, in tokens. Defaults to 8000.
session_idYesLive session_id from steel_session_create.
interactive_onlyNoSkip purely structural containers. On by default; turn off for the full tree.

TDQS

A4.5/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover the read-only safety profile and open-world scope, so the bar is lower. The description adds genuine value: the compact-tree output format, the critical behavioral rule that unreferenced elements cannot be targeted, and a cost/performance comparison ('much cheaper'). Truncation/pagination behavior is left to the schema's cursor parameter, but this is a minor gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Four short sentences with zero filler. The core function is front-loaded first, followed by usage timing, the targeting constraint, and the cheaper alternative. Every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only tool with full annotation coverage, 100% schema description coverage, and no output schema, the description is complete: it explains what is returned, when to call it, what the references mean operationally, and when to prefer a sibling. Nothing an agent needs to invoke it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all four parameters (cursor, max_tokens, session_id, interactive_only) are already documented in the schema. The description does not add parameter-specific detail, so the baseline 3 applies — the schema carries the load and does so adequately.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: 'Return the page as a compact accessibility tree with a @eN reference on every element you can click or type into.' The distinctive @eN reference format makes the output immediately recognizable, and the mention of steel_find as an alternative helps differentiate it from at least one sibling.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides explicit when-to-use guidance ('This is the read to use before acting'), a hard constraint that shapes usage ('Elements with no reference cannot be targeted'), and names the alternative with the condition that selects it ('If you already know what you are looking for, steel_find is much cheaper').

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

steel_wait_forWait for something on the pageA
Read-only

Wait for named text, a CSS selector or URL substring; pass at least one.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlNoWait for the URL to contain this string.
textNoWait for this text to appear on the page.
selectorNoWait for an element matching this CSS selector.
session_idYesLive session_id from steel_session_create.
timeout_msNoGive up after this long.

TDQS

A3.6/5.0
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description conveys the core waiting behavior and clarifies that conditions are alternatives. Annotations already mark the tool as read-only and open-world, so the safety profile is covered. It does not disclose timeout failure behavior, polling semantics, or what happens if multiple conditions are passed, but for a simple wait operation the stated behavior is reasonably transparent.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is one compact sentence with no wasted words. It front-loads the action and immediately enumerates the supported condition types, followed by the key invocation constraint.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The core invocation details are covered by the schema and the at-least-one note. However, there is no output schema and the description does not explain what happens on timeout or what a successful wait returns, which an agent may need to know for robust usage.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, but the description adds meaningful parameter semantics by mapping 'named text', 'CSS selector', and 'URL substring' to the optional text, selector, and url fields. It also adds the at-least-one constraint, which the schema does not enforce.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb and resource: wait for page conditions including text, CSS selector, or URL substring. This avoids tautology and gives an agent a clear sense of what the tool does, though it does not explicitly contrast with sibling tools like steel_find or steel_snapshot.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The phrase 'Wait for...' implies the tool should be used when a page condition must be awaited, and 'pass at least one' gives a necessary precondition. However, it does not provide explicit guidance on when to choose this tool over alternatives or when not to use it.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 25 tool updatesv2.0.1
    • Removedclick
    • Removedgo_back
    • Removednavigate
    • Removedsave_unmarked_screenshot
    • Removedscroll_down
    • Removedscroll_up
    • Removedsearch
    • Addedsteel_act
    • Addedsteel_batch
    • Addedsteel_find
    • Addedsteel_navigate
    • Addedsteel_pdf
    • Addedsteel_scrape
    • Addedsteel_screenshot
    • Addedsteel_session_create
    • Addedsteel_session_diagnostics
    • Addedsteel_session_handoff
    • Addedsteel_session_live_view
    • Addedsteel_session_options
    • Addedsteel_session_release
    • Addedsteel_session_replay
    • Addedsteel_snapshot
    • Addedsteel_wait_for
    • Removedtype
    • Removedwait
  2. 9 tool updatesv1.0.0
    • First observedclick
    • First observedgo_back
    • First observednavigate
    • First observedsave_unmarked_screenshot
    • First observedscroll_down
    • First observedscroll_up
    • First observedsearch
    • First observedtype
    • First observedwait

TDQS

A3.5/5.0

Scored across 16 tools

Disambiguation4/5

Most tools have clearly distinct purposes, with stateless reading (scrape, screenshot, pdf) separated from session interaction (navigate, act, snapshot). A few pairs like steel_screenshot/steel_snapshot and steel_session_live_view/steel_session_replay have similar names, but detailed descriptions resolve the boundaries.

Naming Consistency4/5

All tools share the steel_ prefix and snake_case, but the pattern mixes bare verbs (scrape, navigate, act) with session_ prefixed noun_verb forms (session_create, session_release, session_handoff). This is consistent enough to be predictable, with minor deviations like steel_pdf and steel_wait_for.

Tool Count4/5

16 tools is slightly above the typical 3-15 range, but the breadth covers stateless captures, session lifecycle, element targeting, and diagnostics. Each tool addresses a distinct need, so the count feels justified rather than bloated.

Completeness4/5

The surface covers the core browser automation lifecycle: create/release sessions, navigate, read, interact, wait, and diagnose. Obvious gaps include a full-HTML/markdown read within a live session and session-scoped PDF rendering, but these can be worked around with snapshot or separate stateless calls.

Maintenance

ActivityMaintained
ResponsivenessUnresponsive

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