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Playwright JEV

by rossik86

Playwright MCP + JEV (Browser Intent Layer)

Semantyczny wrapper nad Playwright MCP z autonomicznym modelem decyzyjnym JEV (Decisions API).
Redukuje zużycie tokenów w kontekście głównego LLM o 94% – 99.8%, ukrywa niskopoziomowe drzewo DOM i pozwala na autonomiczną nawigację w stronę celu biznesowego.


📑 Spis Treści

  1. Jak to działa?

  2. Architektura Systemu

  3. Narzędzia MCP (Intent-Only Mode)

  4. Jak Odpalić? (Instalacja i Konfiguracja)

  5. Opcje i Flagi Uruchomieniowe

  6. Wyniki Benchmarków na Żywych Portalach

  7. Uruchamianie Benchmarków i Testów


Related MCP server: SpectraBrowser MCP

💡 Jak to działa?

Problem z klasycznym Playwright MCP:

Tradycyjne integracje MCP z przeglądarką zrzucają całe drzewo dostępności (DOM/A11y) bezpośrednio do promptu głównego LLM przy każdym pojedynczym kroku:

  • Na portalach takich jak Orange.pl czy Empik.com pojedynczy snapshot ma od 36 KB do aż 245 KB (ponad 65 000 tokenów!).

  • Kilkukrokowa sesja potrafi zużyć 100 000 – 200 000 tokenów, kosztując kilkadziesiąt centów i błyskawicznie zapychając okno kontekstowe modelu.

  • Ponadto klasyczny MCP eksponuje ponad 20 niskopoziomowych narzędzi mikrozarządzania (browser_click, browser_fill_form, browser_snapshot), których same opisy w promptcie systemowym zajmują ponad 2 500 tokenów i prowokują halucynacje refów selektorów.

Rozwiązanie: Browser Intent Layer (BIL + JEV):

  1. Główny LLM staje się czystym orkiestratorem — wysyła wyłącznie zwięzłą intencję:

    { "goal": "dodaj do koszyka telefon iphone najnowszy z abonamentem najmniejszym i przejdź na dane zamawiającego" }
  2. Drzewo DOM nigdy nie trafia do głównego LLM — zużycie tokenów orchestratora spada z ~65 000 do zaledwie ~150 tokenów (98–99.8% oszczędności).

  3. Lokalny model decyzyjny JEV (Decisions API) — tani, wyspecjalizowany model micro-decyzji analizuje kandydatów i ocenia ich przydatność w skali 0–100% (noul), kosztując ułamki promila grosza per krok.

  4. Wbudowana autonomia i bezpieczeństwo:

    • Automatyczny Consent Bypass neutralizuje blokujące nakładki RODO/cookies (Didomi, OneTrust, CookieBot).

    • LoopDetector chroni przed wpadnięciem w pętle decyzyjne.

    • Safety Escalation Policy eskaluje do głównego LLM tylko wtedy, gdy pewność wyboru spadnie poniżej progu bezpieczeństwa (< 0.60).


🏛️ Architektura Systemu

┌─────────────────────────────────────────────────────────────┐
│                    Główny LLM (Orchestrator)                │
│            Claude 3.5 Sonnet / GPT-4o / Gemini Pro          │
└──────────────────────────────┬──────────────────────────────┘
                               │  { goal: "..." } (~150 tokenów)
                               ▼
┌─────────────────────────────────────────────────────────────┐
│             BROWSER INTENT LAYER (JEV Proxy Server)         │
│                                                             │
│  1. Snapshot Adapter     → pobiera drzewo A11y              │
│  2. Normalizer           → kompresuje i deduplikuje elementy│
│  3. Stop-Words Filter    → eliminuje szum językowy (PL/EN)  │
│  4. Candidate Retriever  → wyłuskuje top 30 kandydatów      │
│  5. JEV Resolver         → model 'noul' (skala 0.0–1.0)     │
│  6. Loop Detector        → wykrywa cykle i limity kroków    │
│  7. Playwright Executor  → zarządza akcjami w Playwright    │
└──────────────────────────────┬──────────────────────────────┘
                               │  Wewnętrzne JSON-RPC (ref / target)
                               ▼
┌─────────────────────────────────────────────────────────────┐
│              Playwright MCP Child + Przeglądarka            │
│                                                             │
│  • Consent Bypass Script (Didomi / OneTrust auto-bypass)    │
│  • 25 000 ms Action Timeout (odporność na ciężkie portale)  │
│  • Silnik Chromium (Headed lub Headless)                    │
└─────────────────────────────────────────────────────────────┘

Kluczowe komponenty (src/jev-proxy/):

  • bil-controller.js — serce pętli decyzyjnej: pobranie snapshotu ➡️ normalizacja ➡️ wybór kandydatów ➡️ rezolucja JEV ➡️ wykonanie akcji lub eskalacja.

  • jev-resolver.js — integracja z OpenRouter Decisions API z niezależnym ocenianiem prawdopodobieństwa w skali 0–100% (noul).

  • candidate-retriever.js — leksykalno-semantyczny filtr kandydatów z mechanizmem eliminacji słów posiłkowych (stop-words).

  • consent-bypass.js — wstrzykiwany do przeglądarki skrypt neutralizujący nakładki cookies/RODO przechwytujące zdarzenia wskaźnika myszy.

  • loop-detector.js — detektor cykli oparty na hashowaniu stanu stron (fingerprinting).

  • playwright-executor.js — jedyny moduł w systemie znający selektory i refy, odpowiedzialny za klikanie, wypełnianie formularzy i obsługę timeoutów.


🧰 Narzędzia MCP (Intent-Only Mode)

Domyślnie serwer działa w trybie Intent-Only Mode, eksponując dla zewnętrznego klienta wyłącznie 7 narzędzi semantycznych:

Narzędzie

Typ

Opis

browser_goal

Semantyczne

Główne narzędzie. Przyjmuje intencję użytkownika ({ "goal": "..." }) i autonomicznie prowadzi przeglądarkę do celu.

jev_set_context

Kontekst

Ustawienie biznesowego kontekstu sesji (intencji pomocniczej).

browser_navigate

Nawigacja

Bezpośrednie przejście pod podany adres URL.

browser_navigate_back

Nawigacja

Cofnięcie do poprzedniej strony w historii przeglądarki.

browser_take_screenshot

Inspekcja

Wykonanie zrzutu ekranu w razie potrzeby weryfikacji wizualnej przez człowieka.

browser_tabs

Zakładki

Zarządzanie kartami przeglądarki (list, switch, close).

browser_close

Cykl życia

Bezpieczne zamknięcie sesji przeglądarki.

🔒 Dlaczego ukryliśmy niskopoziomowe narzędzia DOM?
W klasycznym MCP narzędzia takie jak browser_click, browser_fill_form, browser_snapshot zaśmiecają prompt klienta (+2 500 tokenów na każde zapytanie) i zmuszają go do mikrozarządzania refami. Ukrycie ich wymusza czystą komunikację intencyjną. W razie potrzeby można je przywrócić flagą --full-tools.


🚀 Jak Odpalić?

Krok 1: Wymagania wstępne

  • Node.js w wersji >= 18

  • Klucz API serwisu OpenRouter z dostępem do modelu Decisions API (domyślnie typesafe/jev-1.13)

Krok 2: Instalacja i konfiguracja .env

# Sklonuj repozytorium i zainstaluj zależności
git clone https://github.com/rossik86/playwright-mcp-jev.git
cd playwright-mcp-jev
npm install

# Utwórz plik .env na podstawie szablonu
cp .env.example .env

Wypełnij plik .env:

JEV_API_KEY=sk-or-v1-twoj_klucz_openrouter
JEV_MODEL=typesafe/jev-1.13
JEV_BASE_URL=https://openrouter.ai/api
INTENT_ONLY=true

Krok 3: Konfiguracja w klientach MCP

Dodaj serwer do konfiguracji swojego klienta MCP (np. mcp.json w Cursor / VS Code / Claude Desktop / Antigravity):

{
  "mcpServers": {
    "playwright-jev": {
      "command": "node",
      "args": [
        "c:/workspace/playwright/src/jev-proxy/cli.js",
        "--headless"
      ],
      "env": {
        "JEV_API_KEY": "sk-or-v1-twoj_klucz_openrouter"
      }
    }
  }
}

Krok 4: Uruchomienie bezpośrednio z linii poleceń (CLI)

# 1. Tryb z widocznym oknem przeglądarki (headed)
node src/jev-proxy/cli.js

# 2. Tryb bezgłowy w tle (headless)
node src/jev-proxy/cli.js --headless

# 3. Uruchomienie z jawnymi parametrami
node src/jev-proxy/cli.js --headless --jev-api-key sk-or-v1-... --jev-model typesafe/jev-1.13

⚙️ Opcje i Flagi Uruchomieniowe

Flaga CLI

Zmienna .env

Domyślnie

Opis

--headless

—

false (headed)

Uruchamia przeglądarkę Chromium w tle (bez GUI)

--intent-only

INTENT_ONLY

true

Domyślny tryb semantyczny — eksponuje tylko 7 narzędzi intencji, ukrywając narzędzia DOM

--full-tools

—

false

Wyłącza intent-only i odsłania pełen zestaw 20+ narzędzi Playwright MCP

--jev-api-key <klucz>

JEV_API_KEY

""

Klucz API do OpenRouter Decisions API

--jev-model <model>

JEV_MODEL

typesafe/jev-1.13

Model używany do podejmowania decyzji

--jev-base-url <url>

JEV_BASE_URL

https://openrouter.ai/api

Adres bazowy API OpenRouter

--timeout-action <ms>

—

25000

Czas oczekiwania na akcje kliknięć w ms (odporność na ciężkie SPA)

--port <port>

—

—

Opcjonalny port HTTP dla transportu SSE


📊 Wyniki Benchmarków na Żywych Portalach

Przetestowano działanie systemu na realnych, złożonych portalach e-commerce i serwisach transakcyjnych w Polsce:

Portal / Scenariusz

Vanilla Playwright MCP (DOM)

Browser Intent Layer (BIL + JEV)

Oszczędność tokenów

Wynik i Zachowanie BIL

GrandBazaar.pl„zamów kebaba aż do danych adresowych”

~2 244 tokenów(7.3 KB drzewa DOM)

~125 tokenów(JEV: 4 979 tok, koszt $0.00017)

94.4% mniej tokenów 🚀

✅ 100% Sukces (3 autonomiczne kroki: strona główna ➡️ menu ➡️ dodanie kebaba ➡️ kasa)

Orange.pl„dodaj telefon iphone z abonamentem i przejdź na dane”

~10 015 – 60 000+ tokenów(36.3 KB – 73 KB na krok)

~201 tokenów(JEV: 12 077 tok, koszt $0.00043)

98.0% mniej tokenów 🚀

🔄 4 autonomiczne kroki przez konfigurator z automatycznym ominięciem Didomi CMP

Empik.com„dodaj książkę Stephen King Misery i przejdź na dane”

~65 766 tokenów!(245.1 KB gigantyczny DOM)

~147 tokenów(JEV: 2 980 tok, koszt $0.00010)

99.8% mniej tokenów! 🚀

🛡️ Safety Escalation (ochrona: model nie kliknął w pusty koszyk przy braku książki na głównej)

📈 Podsumowanie Zysków:

  • Redukcja tokenów kontekstu: o 94.4% – 99.8% w porównaniu z klasycznym zrzucaniem snapshota A11y.

  • Czysty kontekst roboczy: Główny model nie jest zaśmiecany dziesiątkami kilobajtów kodu HTML/DOM.

  • Koszty wykonania: Pojedynczy wieloetapowy proces kosztuje w JEV Decisions API od $0.0001 do $0.0004 (mniej niż pół promila centa), podczas gdy w klasycznym podejściu wysłanie 65 000 tokenów do Claude 3.5 Sonnet / GPT-4o kosztuje $0.20 – $0.50 za pojedynczy krok.


🧪 Uruchamianie Benchmarków i Testów

W projekcie przygotowano dedykowane skrypty npm ułatwiające uruchamianie benchmarków i testów jednostkowych:

# 1. Uruchomienie benchmarku dla konkretnych portali:
npm run bil:benchmark:grandbazaar   # GrandBazaar.pl (kebab kraftowy - 100% sukces)
npm run bil:benchmark:orange        # Orange.pl (iPhone + konfigurator planu)
npm run bil:benchmark:empik         # Empik.com (Stephen King Misery - 99.8% redukcji)

# 2. Uruchomienie pełnego benchmarku porównawczego dla wszystkich scenariuszy
npm run bil:benchmark:both

# 3. Uruchomienie tylko silnika BIL (z tokenami i kosztami)
npm run bil:benchmark

# 4. Uruchomienie tylko silnika klasycznego Playwright MCP
npm run bil:benchmark:classic

# 5. Uruchomienie zestawu testów jednostkowych (55 testów, 100% pass)
npm run bil:test

Available Tools

25 tools
browser_clickB
Destructive

Perform click on a web page

ParametersJSON Schema
NameRequiredDescriptionDefault
buttonNoButton to click, defaults to left
targetYesExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element
modifiersNoModifier keys to press
doubleClickNoWhether to perform a double click instead of a single click

TDQS

B3.2/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=false and destructiveHint=true, indicating the tool mutates state and can be destructive. The description adds no further behavioral disclosure, such as possible navigation or permission requirements. It does not contradict annotations, but provides no value beyond them.

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

Conciseness4/5

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

The description is a single concise sentence with no filler. However, it is terse and omits useful context that could be added without bloat, such as the requirement for a snapshot target. It is appropriately sized but not front-loaded with any distinguishing information.

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?

Given the tool's moderate complexity (5 parameters, no output schema), the description alone is minimally sufficient because the schema fully describes parameters. However, it lacks context about return values, when to use click vs other actions, and potential side effects. The schema covers parameter semantics, so a score of 3 is appropriate.

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%, with every parameter documented (e.g., target is 'Exact target element reference from the page snapshot, or a unique element selector'). The description itself adds no additional parameter meaning, so the baseline of 3 applies.

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 ('Perform click') and the resource ('web page'), which is specific enough. However, it does not differentiate from sibling interaction tools like browser_hover or browser_drag; the agent must infer that 'click' is a distinct action without additional context. It is unambiguous about the core operation but lacks detail on the target element requirement.

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 provides no guidance on when to use this tool versus alternatives. It does not mention prerequisites such as needing a page snapshot to obtain a valid target, nor does it contrast with browser_hover or browser_drag. An agent receives no context for tool selection.

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

browser_closeB
Destructive

Close the page

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

B3.3/5.0
Behavior2/5

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

The annotation already indicates destructiveHint=true, so the agent knows the action is destructive. The description simply repeats that by saying 'close' without adding any extra context about side effects (e.g., whether it closes just the current tab, loses unsaved state, or affects other tabs). It does not contradict the annotation, but it adds no new behavioral information.

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 extremely concise, using only three words. It communicates the essential action and target without any fluff, making it easy to parse and understand quickly.

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?

Given the simplicity of the tool (no parameters, no output schema), the description is functional but lacks completeness. It leaves open the scope of 'close'—does it close the current page/tab, or the entire browser? In a context with sibling tools like browser_tabs, this ambiguity could be problematic. More detail would improve it.

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?

There are no parameters, so the schema coverage is trivially complete at 100%. The description does not need to explain any parameter semantics, and the baseline score of 3 applies.

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 'Close the page' clearly states the action (close) and the resource (page), making it unambiguous. It is distinct from sibling tools like browser_navigate or browser_snapshot, so an agent can easily identify it.

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 provides no guidance on when to use this tool versus alternatives. It does not mention potential alternatives (e.g., using browser_tabs to manage multiple pages) or any conditions that would make closing appropriate. The context is minimal and leaves the decision entirely to the agent.

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

browser_console_messagesC
Read-only

Returns all console messages

ParametersJSON Schema
NameRequiredDescriptionDefault
allNoReturn all console messages since the beginning of the session, not just since the last navigation. Defaults to false.
levelYesLevel of the console messages to return. Each level includes the messages of more severe levels. Defaults to "info".info
filenameNoFile name to save the console messages to. Relative file names are resolved against the workspace root. If not provided, messages are returned as text.

TDQS

C2.9/5.0
Behavior2/5

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

The free-text adds almost no behavioral nuance beyond what annotations already provide. It does not mention the default scope of 'after navigation' versus 'from the session start' (controlled by the 'all' flag), nor the possibility of saving to a file rather than returning text. The sentence simply restates the resource name without additional procedural insight.

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

Conciseness4/5

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

The one-sentence description is extremely concise and free of unnecessary wording, front-loading the main idea efficiently. It could be longer, but as a brief summary it is appropriately structured and not bloated.

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?

The tool's behavior is actually nuanced—console messages can be filtered by severity level and can be limited to the current page. The description fails to explain the return format ( text or file) or the existence of these parameters/capabilities. Without supplemental information from the schema, an agent might assume 'all' means all severities whereas only retrieving info-level messages by default is the actual outcome.

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 provides complete descriptions for all 3 parameters and covers 100% of them, so the baseline is adequate. The description adds no extra meaning about level filtering, filename handling, or the interaction between 'all' and 'level'; it does not conflict but also does not compensate beyond the schema.

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 states a specific resource ('console messages') and a specific action ('Returns'), and the tool name confirms this. It can be clearly distinguished from sibling tools like browser_network_requests or browser_snapshot, which address different browser features. However, the word 'all' is slightly misleading because the level parameter actually filters output.

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 about when to use this tool versus alternatives, nor any mention of typical use cases, prerequisites, or exclusions. The description only states the core product and does nothing to route an agent to the correct selection between this and related browser tools.

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

browser_dragA
Destructive

Perform drag and drop between two elements

ParametersJSON Schema
NameRequiredDescriptionDefault
endTargetYesExact target element reference from the page snapshot, or a unique element selector
endElementNoHuman-readable target element description used to obtain the permission to interact with the element
startTargetYesExact target element reference from the page snapshot, or a unique element selector
startElementNoHuman-readable source element description used to obtain the permission to interact with the element

TDQS

A3.6/5.0
Behavior3/5

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

Annotations already indicate destructiveHint=true and readOnlyHint=false, so the destructive nature is covered. The description adds no extra behavioral context such as side effects on the DOM or event firing, but 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 a single concise sentence that front-loads the action and provides the core information without any irrelevant detail.

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 simple action with well-described parameters and no output schema, the description is mostly complete. It does not mention any return values or wait behavior, but the lack of output schema makes this acceptable. It could have added a note about the order of start and end parameters, but the parameter names and descriptions handle that.

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% with all four parameters described. The tool description adds no additional parameter semantics beyond what the schema already provides, so the baseline of 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 clearly states the action (perform drag and drop) and the resource (between two elements), distinguishing it from sibling tools like browser_click, browser_hover, and browser_drop. It is specific and unambiguous.

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 does not provide any guidance on when to use this tool versus alternatives. It does not mention conditions such as needing to move an element or triggering drag-and-drop events, nor does it reference sibling tools like browser_drop or browser_click.

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

browser_dropA
Destructive

Drop files or MIME-typed data onto an element, as if dragged from outside the page. At least one of "paths" or "data" must be provided.

ParametersJSON Schema
NameRequiredDescriptionDefault
dataNoData to drop, as a map of MIME type to string value (e.g. {"text/plain": "hello", "text/uri-list": "https://example.com"}).
pathsNoAbsolute paths to files to drop onto the element.
targetYesExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element

TDQS

A4/5.0
Behavior3/5

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

Annotations already convey destructive and non-read-only behavior, so the description does not need to repeat that. The description adds useful semantic context about simulating an external drag, but does not disclose any side effects beyond the basic drop action.

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 a single, focused sentence that concisely explains both the action and the key parameter requirement. No filler or redundancy.

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?

The description, combined with the detailed schema and annotations, provides enough information to invoke the tool correctly. There is no output schema, so return-value details are not required, and the parameter permission explanation is handled by the 'element' field description.

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?

All parameters have clear schema descriptions. The tool description adds an important cross-parameter constraint that at least one of 'paths' or 'data' must be provided, which is not otherwise expressed 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 clearly states the action: dropping files or MIME-typed data onto an element. It uses a specific verb and resource, and distinguishes itself from in-page drag operations by specifying 'as if dragged from outside the page'.

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 gives a useful usage constraint ('At least one of paths or data must be provided') and hints at external drag context, but it does not explicitly name sibling tools or state when to prefer this over browser_file_upload or browser_drag.

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

browser_emulate_mediaA
Destructive

Emulate CSS media features for the page, for example switch between the light and dark color scheme. Omitted parameters are left unchanged; null clears an override.

ParametersJSON Schema
NameRequiredDescriptionDefault
mediaNoChanges the CSS media type of the page
contrastNoEmulates the prefers-contrast media feature
colorSchemeNoEmulates the prefers-color-scheme media feature
forcedColorsNoEmulates the forced-colors media feature
reducedMotionNoEmulates the prefers-reduced-motion media feature

TDQS

A4.2/5.0
Behavior4/5

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

Annotations already signal a non-read-only, potentially destructive operation. The description adds genuine behavioral nuance: omitted parameters are left unchanged, and null clears an override, which clarifies how state mutates and how to reset it. This adds value beyond the annotations without contradicting them.

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: the first states the tool's purpose with an example, and the second states the omission/null behavior. No filler is present, and the primary action 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 tool with five optional parameters and complete schema coverage, the description is largely sufficient. It lacks explicit details about persistence scope or how to clear all overrides at once, but the null-clears-override rule and the schema fill most practical gaps.

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?

The input schema already documents all five parameters thoroughly, so the baseline is 3. The description adds a cross-cutting semantic not present in the schema: omitted parameters remain unchanged while null clears an override. This distinction is essential for correct invocation.

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 ('Emulate'), names the resource ('CSS media features for the page'), and includes a concrete light/dark example. This clearly distinguishes it from the sibling browser tools and tells an agent exactly what domain it operates on.

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 provides important invocation semantics: omitted parameters are left unchanged, and null clears an override. However, it does not explicitly state when to prefer this tool over alternatives, though the unique purpose among siblings makes the intended context largely inferable.

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

browser_evaluateC
Destructive

Evaluate JavaScript expression on page or element

ParametersJSON Schema
NameRequiredDescriptionDefault
targetNoExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element
filenameNoFile name to save the result to. Relative file names are resolved against the workspace root. If not provided, result is returned as text.
functionYes() => { /* code */ } or (element) => { /* code */ } when element is provided

TDQS

C2.8/5.0
Behavior2/5

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

Annotations already declare destructiveHint=true and readOnlyHint=false, indicating this is a mutating, potentially harmful operation. The description adds no additional behavioral context—no mention of side effects, permission requirements, or what exactly could be destroyed. It essentially restates the tool's name without enriching the safety profile beyond what the annotations already provide.

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

Conciseness3/5

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

The description is extremely concise—a single sentence. While this is efficient, it lacks any structural breakdown or additional context. It is not front-loaded with critical details like safety warnings or usage hints. It is concise but under-specified, missing the balance between brevity and informativeness.

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?

Given the tool's complexity (executes arbitrary JavaScript) and destructive nature, the description is notably incomplete. It does not explain return value format, error handling, or what happens when the function mutates the page. There is no output schema, so the description must cover these aspects, but it fails to do so. The presence of a sibling like browser_run_code_unsafe further highlights the need for differentiation, which is absent.

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 (target, element, filename, function) is documented in the schema. The description adds no extra semantic information about the parameters, such as how the function signature works or how target interacts with element. Since the schema fully covers parameter meanings, a baseline score of 3 is appropriate.

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 ('Evaluate JavaScript expression') and the target ('on page or element'). It is specific enough to convey the core function. However, it does not differentiate from the sibling tool browser_run_code_unsafe, which also executes JavaScript, so the agent might struggle to choose between them based solely on the description.

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 gives no guidance on when to use this tool versus alternatives. It does not mention browser_run_code_unsafe or any other relevant sibling, nor does it state any prerequisites, limitations, or conditions that would steer the agent toward or away from this tool. This leaves the agent without clear decision support.

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

browser_file_uploadB
Destructive

Upload one or multiple files

ParametersJSON Schema
NameRequiredDescriptionDefault
pathsNoThe absolute paths to the files to upload. Can be single file or multiple files. If omitted, file chooser is cancelled.

TDQS

B3.4/5.0
Behavior3/5

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

The annotations already indicate destructive behavior and non-read-only semantics, so the description does not need to restate those. However, the description does not mention side effects beyond uploading, such as navigating away, opening or cancelling a file chooser, or potential overwrite behavior, though the parameter description partially covers the cancellation case.

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 extremely concise and free of filler. Every word contributes meaning, and the parameter description adds necessary details without redundancy.

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?

For a simple one-parameter tool with no output schema, the description and parameter comment cover the essential input and basic behavior. However, it does not describe what happens after the upload, what success or failure looks like, or how this fits into the broader browser automation workflow, leaving some practical context missing.

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?

The schema only defines an array of strings, but the parameter description adds important meaning: paths must be absolute, multiple files are allowed, and omitting the parameter cancels the file chooser. This goes beyond the raw schema and helps an agent use the parameter correctly.

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 ('Upload') and the resource ('files'), and specifies 'one or multiple'. It does not explicitly state the destination or context, but the tool name and sibling set make the browser file-upload intent sufficiently clear.

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 gives no guidance on when to use this tool versus alternatives such as browser_drop or other browser interaction tools. It also does not mention prerequisites like whether the file chooser must already be open or how paths should be formatted beyond 'absolute'.

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

browser_fill_formB
Destructive

Fill multiple form fields

ParametersJSON Schema
NameRequiredDescriptionDefault
fieldsYesFields to fill in

TDQS

B3.2/5.0
Behavior3/5

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

The annotations already declare readOnlyHint=false and destructiveHint=true, so the write and potentially destructive nature is covered. The description adds the 'multiple form fields' detail but does not disclose additional behavior such as overwriting values or submitting the form.

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

Conciseness4/5

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

The description is a single clear sentence with no redundant words or boilerplate. It is appropriately short and easy to parse, though it sacrifices deeper context for brevity.

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?

The rich schema fully documents the nested field objects, including target references, type-specific value behavior, and permission-related element descriptions. Combined with the read-only and destructive annotations, the description is sufficient for correct invocation; only alternative-selection guidance 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 coverage is 100%: the fields array and its nested target, name, type, value, and element properties all have descriptive text. The description itself does not add parameter-level meaning beyond what the schema already provides.

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 'Fill multiple form fields' clearly identifies the action and resource, and the word 'multiple' helps distinguish it from single-field tools like browser_type. It does not explicitly contrast with sibling tools, but the core purpose is unambiguous.

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?

No guidance is provided for when to use this tool instead of alternatives such as browser_type, browser_select_option, or browser_click. The term 'multiple' implies batch usage, but there is no explicit when-to-use or exclusion context.

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

browser_findA
Read-only

Search the accessibility snapshot of the current page for text or a regular expression. Returns matching snapshot nodes with a few lines of surrounding context (like search snippets), each shown under its path from the root of the tree, which is cheaper than capturing the whole snapshot when you only need to locate an element and its ref.

ParametersJSON Schema
NameRequiredDescriptionDefault
textNoPlain text to search for in the page snapshot (case-insensitive substring match). Provide either text or regex, not both.
regexNoRegular expression to search for in the page snapshot. Matching is case-sensitive by default; wrap the pattern in slashes to add flags, e.g. "/error/i" for case-insensitive. Provide either text or regex, not both.

TDQS

A4.2/5.0
Behavior4/5

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

Annotations already cover read-only and non-destructive behavior. The description adds useful behavioral detail about return format, surrounding context, path-from-root presentation, and cost characteristics. It is consistent with the annotations, with no contradictions.

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 dense, well-structured sentence that front-loads the action and then provides the output shape and the key trade-off. There is no filler or redundancy; every clause 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?

The description explains return shape and the main use case, and annotations cover safety. However, since neither parameter is marked required in the schema, the description could more explicitly instruct the agent to provide exactly one of text or regex.

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 coverage is 100%; both text and regex are already documented with mutual exclusivity and regex flag syntax. The description adds no parameter-level meaning beyond restating that either text or regex is used, so the baseline score of 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 states a specific verb ('Search'), a clear resource ('the accessibility snapshot of the current page'), and a well-defined result (matching snapshot nodes with surrounding context and refs). It also distinguishes itself from the whole-snapshot sibling by explaining its narrower focus.

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?

It gives a clear when-to-use condition: this is 'cheaper than capturing the whole snapshot when you only need to locate an element and its ref.' It implicitly contrasts with browser_snapshot but does not explicitly name the sibling or state when NOT to use this tool, so it stops short of full guidance.

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

browser_handle_dialogC
Destructive

Handle a dialog

ParametersJSON Schema
NameRequiredDescriptionDefault
acceptYesWhether to accept the dialog.
promptTextNoThe text of the prompt in case of a prompt dialog.

TDQS

C2.2/5.0
Behavior2/5

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

The annotations indicate readOnlyHint=false and destructiveHint=true, covering the main safety aspect. However, the description adds no detail about side effects, such as submitting a form or canceling a prompt, beyond what the parameter names imply. It does not clearly disclose the consequences of accepting or rejecting.

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 extremely short and lacks necessary detail, making it under-specified. It is terse but not informative enough to guide an agent effectively, similar to a placeholder like 'Process'.

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?

No output schema or additional context is provided. The description does not explain what happens after handling the dialog, how the parameters interact, or any post-conditions. This is insufficient for an agent to fully understand the tool's behavior.

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 coverage is 100% with clear descriptions for both 'accept' (boolean) and 'promptText' (string for prompt dialogs). The description does not add extra meaning, but the schema already provides adequate parameter semantics, so the baseline of 3 is appropriate.

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 'Handle a dialog' identifies the action and resource but is vague. It does not specify the type of dialog (alert, confirm, prompt) or the precise effect, though the 'accept' parameter implies accept/dismiss. It is distinct from sibling tools, but the purpose is under-specified.

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

Usage Guidelines1/5

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

No guidance is provided about when to use this tool, such as after a dialog appears or in contrast to other browser actions. The description gives no context for the appropriate situation.

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

browser_hoverA
Destructive

Hover over element on page

ParametersJSON Schema
NameRequiredDescriptionDefault
targetYesExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element

TDQS

A3.6/5.0
Behavior3/5

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

Annotations already indicate readOnlyHint=false and destructiveHint=true, so the description doesn't need to re-state them. The description adds no extra behavioral detail about side effects (e.g., triggering JavaScript events, potential menu changes). With annotations present, the bar is lower, but there's still room for more transparency about outcomes.

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 extremely concise—six words, no redundancy, and perfectly focused on the action. It follows a clear verb-object structure with no extra fluff, making it easy to parse and understand.

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 simple interaction tool, the description, alongside the parameter schema and annotations, is adequate. It lacks details on return values (but no output schema exists) and does not mention any prerequisites or setup. Given the simplicity, it covers essential context without being overlong.

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?

Both parameters (target and element) have descriptions in the schema, achieving 100% coverage. The tool description does not add further meaning beyond the schema; it simply restates the action. Since schema coverage is complete, a baseline score of 3 is appropriate.

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 (hover) and the target (element on page). It distinguishes itself from sibling tools like click, drag, and type by specifying the hover action. However, it lacks detail about what the hover does (e.g., showing tooltips or hover menus), but the core purpose is clear.

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 gives no explicit guidance on when to use hover versus other interactions. While it's intuitive that hover is for mouse-over actions, the description doesn't mention edge cases or alternative tools (e.g., use click for activating, hover for previews). It provides minimal implicit usage context.

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

browser_navigateC
Destructive

Navigate to a URL

ParametersJSON Schema
NameRequiredDescriptionDefault
urlYesThe URL to navigate to

TDQS

C2.7/5.0
Behavior2/5

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

The description does not elaborate on side effects such as discarding the current page, waiting for load, or handling errors. While annotations indicate destructiveHint=true, the description adds no extra context about the navigation behavior beyond the literal action.

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

Conciseness4/5

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

The description is a single, direct sentence with no unnecessary words. It is appropriately sized for the simple action, though it could benefit from some additional context without becoming verbose.

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?

The description lacks important context such as whether navigation waits for page load, how errors are reported, or the impact on the current browsing session. Given the tool modifies state (as indicated by destructiveHint), more context about the navigation behavior would be expected.

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 schema fully describes the only parameter 'url' with the same text as the description. Since schema coverage is 100%, the description adds no additional meaning or constraints (e.g., format, absolute vs. relative) beyond what is already in the schema.

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 to a URL' with a specific resource. It distinguishes from sibling tools like browser_navigate_back by implying forward navigation to a new URL, though it could be more explicit about the effect on the current page.

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

Usage Guidelines1/5

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

No guidance is provided on when to use this tool over alternatives. It does not mention scenarios where browser_navigate is preferred over browser_navigate_back or other navigation methods, nor any prerequisites or exclusions.

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

browser_navigate_backA
Destructive

Go back to the previous page in the history

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A3.7/5.0
Behavior3/5

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

The description and annotations are consistent; destructiveHint is true, matching the navigation action which changes the current page. The description adds minimal behavioral context beyond the annotations, but does not contradict them. It does not mention potential side effects like what happens if there is no history or whether it affects new tabs.

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 a single, concise sentence with no redundant wording. It directly states the action and target without unnecessary detail, which is ideal for a tool with no parameters.

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 simple, parameterless tool, the description is largely complete. It communicates the essential operation. It could be improved by noting the behavior when there is no previous history entry, but the given context is sufficient for most use cases.

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?

The tool has zero parameters, so the description does not need to explain parameter semantics. The empty input schema is fully covered by the lack of parameters, making this baseline appropriate.

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: 'Go back to the previous page in the history.' It identifies the resource (browser history) and the direction (back), making the core purpose unambiguous. It does not explicitly differentiate from sibling tools like browser_navigate or browser_tabs, but the meaning is clear enough in context.

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 the tool: when the user wants to go back to the previous page in history. However, it provides no explicit guidance on when not to use it, such as when a direct URL navigation via browser_navigate would be more appropriate, or what to do if no prior history exists.

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

browser_network_requestA
Read-only

Returns full details (headers and body) of a single network request, or a single part if part is set. Use the number from browser_network_requests.

ParametersJSON Schema
NameRequiredDescriptionDefault
partNoReturn only this part of the request. Omit to return full details.
indexYes1-based index of the request, as printed by browser_network_requests.
filenameNoFile name to save the result to. Relative file names are resolved against the workspace root. If not provided, output is returned as text.

TDQS

A4/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so no safety disclosure is needed. The description adds that the result includes headers and body and that `part` narrows the output, but it does not describe deeper behavior such as response size, formatting, or error cases. This is acceptable for a read-only 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 a single focused sentence plus one essential usage pointer. No filler, and the core behavior is front-loaded before the optional part behavior.

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 simple read-only retrieval tool with one required parameter and complete schema descriptions, the description covers the essential invocation path: select a request from the list, optionally choose a part, and get full details. It does not explain output structure beyond 'headers and body,' but no output schema exists and the tool's behavior is straightforward.

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 fully documents index, part, and filename. The description's mention of `part` and the index reference restates schema content rather than adding new meaning. 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 uses a specific verb-resource pair ('Returns full details ... of a single network request') and immediately contrasts with the plural sibling by referencing the index from browser_network_requests. This makes the tool's singular, detail-retrieval role unmistakable.

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?

It gives clear context: use an index obtained from browser_network_requests, and optionally narrow to one part via `part`. It does not explicitly state when not to use this tool versus alternatives, but the singular-vs-list relationship to the sibling is clear enough.

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

browser_network_requestsA
Read-only

Returns a numbered list of network requests since loading the page. Use browser_network_request with the number to get full details.

ParametersJSON Schema
NameRequiredDescriptionDefault
filterNoOnly return requests whose URL matches this regexp (e.g. "/api/.*user").
staticYesWhether to include successful static resources like images, fonts, scripts, etc. Defaults to false.
filenameNoFile name to save the network requests to. Relative file names are resolved against the workspace root. If not provided, requests are returned as text.

TDQS

A4.5/5.0
Behavior4/5

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

Annotations already indicate readOnlyHint=true and destructiveHint=false. The description adds useful behavioral context by noting the list is numbered and scoped to requests since page load, plus it explicitly points to the companion tool for deeper inspection. 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 tight sentences, with the core behavior first and the routing instruction second. Every sentence earns its place and there is no redundant wording.

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 listing tool, the description explains what is returned, the page-load scope, and the natural next step for details. The input schema handles parameter semantics and filename behavior, 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 fully documents filter, static, and filename. The tool description does not add parameter-level details, but it does not need to because the schema already carries that burden.

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 states a specific verb and resource: 'Returns a numbered list of network requests since loading the page.' It also explicitly distinguishes the tool from its sibling browser_network_request by telling the agent to use that sibling with a number for full details.

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 gives a clear workflow: list requests here, then call browser_network_request with the number for details. This directly tells the agent when to use this tool versus the relevant alternative.

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

browser_press_keyB
Destructive

Press a key on the keyboard

ParametersJSON Schema
NameRequiredDescriptionDefault
keyYesName of the key to press or a character to generate, such as `ArrowLeft` or `a`

TDQS

B3.2/5.0
Behavior2/5

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

The description does not mention any side effects, such as triggering keyboard events or potential destructive behavior. The annotations indicate destructiveHint: true, but the description adds no additional behavioral context beyond that.

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 extremely concise — a single sentence that directly conveys the action. No unnecessary information or repetition.

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 simple action with a single well-defined parameter, the description is adequate. It lacks mention of when to use this tool (e.g., for shortcuts or navigation keys) but is otherwise complete for basic 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?

The parameter 'key' is fully described in the schema with examples, and schema coverage is 100%. The description adds minimal extra meaning ('on the keyboard') but doesn't clarify key formats or special keys, which is already covered by the schema.

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 (press) and the resource (key on the keyboard). It is distinct from broader actions like navigate or click, though it does not explicitly differentiate from browser_type (typing) or browser_click (clicking).

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?

No guidance is provided on when to use this tool versus its siblings (e.g., browser_type for text entry or browser_click for mouse actions). The description lacks any contextual cues for choosing this tool.

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

browser_resizeB
Destructive

Resize the browser window

ParametersJSON Schema
NameRequiredDescriptionDefault
widthYesWidth of the browser window
heightYesHeight of the browser window

TDQS

B3.1/5.0
Behavior2/5

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

The description does not disclose any behavioral traits beyond the bare action. Annotations already indicate it is not read-only and is destructive, but the description adds no extra context about side effects like layout reflows or potential viewport changes.

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 a single, short declarative sentence with no unnecessary words. It is perfectly concise and well-structured for the simple action it describes.

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?

For a simple tool, the description is adequate, but it lacks any extra context such as units (e.g., pixels), constraints, or when resizing might be appropriate. Given the simplicity and schema coverage, it is minimally complete but not rich.

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 descriptions for both parameters (width and height), achieving 100% coverage. The description adds no additional meaning about the parameters, so it stays at the baseline of 3.

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 (resize) and the resource (browser window), making it distinct from sibling tools like navigate or click. However, it lacks any nuance about whether it resizes the viewport or the entire window, but the core purpose is clear.

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?

No guidance is provided about when to use this tool versus alternatives. It does not mention scenarios like adjusting viewport for responsive testing or any conditions that would make it preferable to other navigation tools.

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

browser_run_code_unsafeA
Destructive

Run a Playwright code snippet. Unsafe: executes arbitrary JavaScript in the Playwright server process and is RCE-equivalent.

ParametersJSON Schema
NameRequiredDescriptionDefault
codeNoA JavaScript function containing Playwright code to execute. It will be invoked with a single argument, page, which you can use for any page interaction. For example: `async (page) => { await page.getByRole('button', { name: 'Submit' }).click(); return await page.title(); }`
filenameNoLoad code from the specified file. Relative file names are resolved against the workspace root. If both code and filename are provided, code will be ignored.

TDQS

A4.4/5.0
Behavior5/5

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

Even though destructiveHint=true and readOnlyHint=false already signal danger, the description adds crucial context: the code runs in the Playwright server process, can execute arbitrary JavaScript, and is RCE-equivalent. This is more transparent than the annotation alone and gives an agent a concrete safety boundary.

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 short sentences deliver the action, the resource, the execution context, and a stark safety warning. Every word earns its place, and the danger is front-loaded immediately after the verb.

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 dangerous arbitrary-code tool with no output schema, the description gives the critical context an agent needs: where the code runs and why it is unsafe. It does not describe the return value or error behavior, but given the open-ended nature of the tool and the complete parameter schema, this is a minor gap.

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%, and both 'code' and 'filename' are already well documented in the schema, including the precedence rule when both are provided. The description adds no parameter-specific meaning, but it does not need to because the schema carries the full burden.

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 ('Run'), a specific resource ('a Playwright code snippet'), and immediately identifies the defining scope: arbitrary JavaScript in the Playwright server process. This clearly sets it apart from sibling tools like browser_evaluate, which executes in the page, even though both are code-execution 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 does not name alternatives explicitly, but the 'Unsafe' and 'RCE-equivalent' framing strongly implies this is a last-resort escape hatch rather than a routine tool. It gives enough context for an agent to know it should prefer the safer specialized browser sibling tools unless it truly needs arbitrary Playwright code.

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

browser_select_optionB
Destructive

Select an option in a dropdown

ParametersJSON Schema
NameRequiredDescriptionDefault
targetYesExact target element reference from the page snapshot, or a unique element selector
valuesYesArray of values to select in the dropdown. This can be a single value or multiple values.
elementNoHuman-readable element description used to obtain permission to interact with the element

TDQS

B3.4/5.0
Behavior3/5

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

Annotations already indicate destructive=true, so the description does not contradict that. But the description adds no further behavioral detail (e.g., side effects on the page). With annotations present, the bar is lower, and the description is neutral.

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 a single concise sentence with no redundant words. It is well-structured and to the point.

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?

The tool is simple and the schema covers all parameters. The description is short but sufficient for a basic understanding. It does not specify whether values are labels or values, but that is a minor omission given the context.

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 coverage is 100% with clear parameter descriptions for target and values. The tool description itself does not explain parameters beyond what the schema already provides, so it adds no extra semantic value.

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 (select) and the target (option in a dropdown), distinguishing it from more general actions like click or type. However, it does not explicitly contrast with sibling tools, so it misses a bit of distinction.

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 provides no guidance on when to use this tool versus alternatives. It does not mention when selecting is appropriate or when other actions (e.g., click, type) might be preferred.

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

browser_snapshotA
Read-only

Capture accessibility snapshot of the current page, this is better than screenshot

ParametersJSON Schema
NameRequiredDescriptionDefault
boxesNoInclude each element's bounding box as [box=x,y,width,height] in the snapshot. Coordinates are viewport-relative, in CSS pixels (Element.getBoundingClientRect)
depthNoLimit the depth of the snapshot tree
targetNoExact target element reference from the page snapshot, or a unique element selector
filenameNoSave snapshot to a file instead of returning it in the response. Relative file names are resolved against the workspace root.

TDQS

A4/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds that the result is an accessibility snapshot rather than a visual screenshot, which is useful behavioral context, but it does not describe the output structure or any other side effects. With annotations present, this is adequate but not rich.

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 a single efficient sentence that front-loads the action and object. The comparative note about screenshots earns its place by helping tool selection without adding bloat.

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?

The tool is simple, read-only, and all parameters are documented in the schema. The description covers the core behavior and differentiates from screenshots, though it could be slightly more explicit about what the returned accessibility snapshot contains given there is no output schema.

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%, with all four parameters clearly documented in the input schema. The description itself adds no parameter-level meaning, so the baseline of 3 applies.

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 states a specific verb ('Capture') and resource ('accessibility snapshot of the current page'), making the tool's function immediately clear. It also distinguishes itself from the screenshot alternative, which is directly relevant to sibling browser_take_screenshot.

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 phrase 'this is better than screenshot' provides a clear comparison and implicit routing away from browser_take_screenshot. However, it does not explicitly state when not to use this tool or list other alternatives, so the guidance is context rather than a full routing rule.

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

browser_tabsA
Destructive

List, create, close, or select a browser tab.

ParametersJSON Schema
NameRequiredDescriptionDefault
urlNoURL to navigate to in the new tab, used for new.
indexNoTab index, used for close/select. If omitted for close, current tab is closed.
actionYesOperation to perform

TDQS

A3.5/5.0
Behavior2/5

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is known. However, the description adds no behavioral context beyond what the schema provides (e.g., index omission for close closes current tab is in schema). No mention of side effects like tab switching or browser-level changes.

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 a single sentence that efficiently lists all supported actions. It is front-loaded with verbs and avoids unnecessary words.

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 tool has multiple actions and a required action parameter. The description lists the actions but does not explain action-specific requirements (e.g., URL required for new, index for close/select) or edge cases like closing the last tab. Given the schema covers parameter details, the description is adequate but not rich. With no output schema, the agent must infer return values from the action.

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% with each parameter having a description (url, index, action with enum). The tool description adds no parameter-level detail, so it does not go beyond schema. Baseline 3 applies.

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 clearly states the tool's purpose with specific verbs (list, create, close, select) and a specific resource (browser tab). It distinguishes from siblings like browser_close (closes the entire browser) and browser_navigate (navigates current tab) by focusing on tab operations.

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 usage through the list of actions but provides no explicit when-to-use guidance or exclusions. Given siblings like browser_close (closes the entire browser) and browser_navigate (navigates current tab), an agent might benefit from explicit differentiation, but the actions themselves are clear enough that usage is implied.

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

browser_take_screenshotA
Read-only

Take a screenshot of the current page. You can't perform actions based on the screenshot, use browser_snapshot for actions.

ParametersJSON Schema
NameRequiredDescriptionDefault
typeNoImage format for the screenshot. If unset, inferred from the filename extension, otherwise png.
scaleYesImage resolution scale. "css" produces a screenshot sized in CSS pixels (smaller, consistent across devices). "device" produces a high-resolution screenshot using device pixels (larger, accounts for the device pixel ratio). Default is css.css
targetNoExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element
filenameNoFile name to save the screenshot to. Relative file names are resolved against the workspace root. If not specified, the screenshot is saved into the output directory as `page-{timestamp}.{png|jpeg|webp}`.
fullPageNoWhen true, takes a screenshot of the full scrollable page, instead of the currently visible viewport. Cannot be used with element screenshots.

TDQS

A4.4/5.0
Behavior4/5

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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false), so the bar is lower. The description adds one meaningful behavioral trait beyond annotations: the screenshot is a passive artifact that cannot drive actions. However, it leaves file-saving/output behavior to the schema's filename parameter rather than disclosing it in prose.

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 short sentences, each earning its place: the first states the operation, the second carries the critical usage caveat and sibling routing. No filler or repetition of 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?

For a read-only tool with a 100%-coverage schema and safety annotations, the definition is nearly complete: purpose, key caveat, and alternative routing are all present. A somewhat richer description could orient agents toward element/fullPage screenshot capabilities, though the schema already documents these.

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%, with detailed documentation for all six parameters including enum semantics (type, scale), defaults, and interaction constraints (fullPage cannot be used with element screenshots). The description adds nothing beyond the schema, so the baseline 3 applies.

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 states a specific verb and resource ('Take a screenshot of the current page') and distinguishes itself from a sibling by noting 'use browser_snapshot for actions.' The action and scope are unambiguous, and the read-only intent matches 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 Guidelines5/5

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

The description explicitly tells the agent when NOT to use this tool ('You can't perform actions based on the screenshot') and names the exact alternative ('use browser_snapshot for actions'). This is direct when/when-not routing with no inference required.

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

browser_typeB
Destructive

Type text into editable element

ParametersJSON Schema
NameRequiredDescriptionDefault
textYesText to type into the element
slowlyNoWhether to type one character at a time. Useful for triggering key handlers in the page. By default entire text is filled in at once.
submitNoWhether to submit entered text (press Enter after)
targetYesExact target element reference from the page snapshot, or a unique element selector
elementNoHuman-readable element description used to obtain permission to interact with the element

TDQS

B3/5.0
Behavior3/5

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

The annotation destructiveHint=true and readOnlyHint=false already signal that this tool can modify state, so the description does not contradict that. However, the main description adds no additional behavioral context beyond the annotations, such as whether typing overwrites existing content or triggers page events. The parameter descriptions do mention key-handler triggering and Enter submission, but the main description itself stays shallow.

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 a single, focused sentence with no filler or repetition. It front-loads the verb and object, making the tool's primary purpose immediately obvious.

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 several closely related siblings (fill_form, press_key, click), the description is too thin to fully orient an agent. It lacks any mention of when typing is appropriate, how the target is resolved, or what side effects to expect, so the agent must rely on parameter descriptions and external context to make a confident choice.

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 coverage is 100%, so the baseline is 3 because the input schema already documents all five parameters. The main description, 'Type text into editable element,' adds no meaning beyond the schema's parameter descriptions, which already define text, slowly, submit, target, and element clearly enough.

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 states a clear action ('Type text') and a clear target ('editable element'), which distinguishes it from many sibling tools at a high level. It is slightly vague about whether 'editable element' includes textareas, contenteditable regions, or only input fields, but the core purpose is unambiguous.

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

Usage Guidelines1/5

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

The description gives no guidance on when to prefer this tool over sibling tools such as browser_fill_form or browser_press_key. It does not mention exclusions, prerequisites, or scenarios where typing would be inappropriate, leaving the agent to infer usage from the tool name alone.

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

browser_wait_forA
Read-only

Wait for text to appear or disappear or a specified time to pass

ParametersJSON Schema
NameRequiredDescriptionDefault
textNoThe text to wait for
timeNoThe time to wait in seconds
textGoneNoThe text to wait for to disappear

TDQS

A3.9/5.0
Behavior4/5

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

The description adds behavioral detail beyond the readOnlyHint by explaining that it waits for text appearance/disappearance or a time delay. However, it does not specify what happens if multiple parameters are provided or if none are provided, so behavior is not fully 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 a single concise sentence that front-loads the core action and conditions. It contains no unnecessary words and is easy to parse.

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?

For a simple wait tool with no output schema, the description covers the main use cases, but it omits edge cases such as default behavior when no parameters are supplied, timeout behavior, or error conditions. These gaps make it only partially 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?

The schema descriptions already cover each parameter individually, and the tool description mostly restates them. It does not clarify the relationship between text, textGone, and time (e.g., whether they are mutually exclusive or combinable), so minimal semantic value is added 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 clearly states the tool waits for a condition: text to appear, text to disappear, or a specified time to pass. This distinguishes it from sibling tools like click, navigate, or type, and its purpose is immediately understandable.

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 the tool (when waiting for page state or a delay), but it does not explicitly state when to prefer this over alternatives or how to choose among text, textGone, and time parameters. It provides functional guidance but lacks explicit usage conditions.

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 updatesv0.0.82
    • First observedbrowser_click
    • First observedbrowser_close
    • First observedbrowser_console_messages
    • First observedbrowser_drag
    • First observedbrowser_drop
    • First observedbrowser_emulate_media
    • First observedbrowser_evaluate
    • First observedbrowser_file_upload
    • First observedbrowser_fill_form
    • First observedbrowser_find
    • First observedbrowser_handle_dialog
    • First observedbrowser_hover
    • First observedbrowser_navigate
    • First observedbrowser_navigate_back
    • First observedbrowser_network_request
    • First observedbrowser_network_requests
    • First observedbrowser_press_key
    • First observedbrowser_resize
    • First observedbrowser_run_code_unsafe
    • First observedbrowser_select_option
    • First observedbrowser_snapshot
    • First observedbrowser_tabs
    • First observedbrowser_take_screenshot
    • First observedbrowser_type
    • First observedbrowser_wait_for

TDQS

B3.4/5.0

Scored across 25 tools

Disambiguation4/5

Most tools target distinct browser actions (click, hover, type, navigate, snapshot, screenshot). A few pairs overlap somewhat — browser_drop vs browser_drag, and browser_evaluate vs browser_run_code_unsafe — but descriptions clarify their boundaries well enough to select correctly.

Naming Consistency5/5

Every tool uses the browser_ prefix with consistent snake_case verb/noun phrasing (browser_navigate, browser_take_screenshot, browser_select_option). The pattern is uniform and predictable across all 25 tools.

Tool Count4/5

25 tools is on the heavy side, but browser automation is a genuinely broad domain and nearly every tool covers a distinct capability (dialogs, network, console, tabs, media emulation). Slightly over-scoped but each tool earns its place.

Completeness4/5

The surface covers the full interaction lifecycle: navigation, interaction, forms, dialogs, file upload, network/console inspection, and screenshots. Minor gaps like explicit cookie/localStorage management exist, but agents can work around them via browser_evaluate.

Maintenance

ActivityActive
ResponsivenessNo issues

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