cdt-smart-snapshot
This server provides token-efficient page perception and interaction tools via CDP, complementing the official Chrome DevTools MCP server by dramatically reducing token consumption (e.g., up to 94% reduction on some sites). Key capabilities:
Smart Snapshot: Capture a concise semantic snapshot of visible and interactive elements, with depth limiting and deduplication.
Snapshot Diff: Get only the changes (added/removed/modified) between snapshots for efficient incremental updates.
Screenshot to Disk: Save screenshots directly to disk (PNG/JPEG, full-page), returning file paths instead of base64 to save ~3,000–5,000 tokens.
Page Search: Search the snapshot tree by keyword (case-insensitive) to quickly find elements by role, name, and path.
Node Details: Retrieve detailed info (role, path, geometry, CSS selector) for a specific node by UID.
Element to Selector: Convert a snapshot UID to a unique CSS selector for use with other automation tools (e.g., click/fill).
Page Status: Monitor current URL, title, loading state, console errors, page exceptions, and failed network requests.
Snapshot Index: List all UIDs from the latest snapshot for debugging or exploration.
Provides token-efficient page snapshots, diffing, search, and screenshot tools for a running Google Chrome (or Chromium) browser via the Chrome DevTools Protocol, enabling agents to perceive and query page state.
Click on "Install Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@cdt-smart-snapshotTake a smart snapshot of the current page."
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
cdt-smart-snapshot
Token-efficient snapshot MCP server for Chrome DevTools Protocol.
Use alongside official chrome-devtools-mcp:
operations (click / fill / navigate) stay on the official server; page perception
(smart_snapshot / snapshot_diff / screenshot_to_disk) goes through this server.
Install
npm (recommended):
npm install -g cdt-smart-snapshot
# or run without installing: npx cdt-smart-snapshotFrom source (developers):
git clone https://github.com/sinnhirl/cdt-smart-snapshot
cd cdt-smart-snapshot
npm install
npm run buildRequires Node.js ^20.19 || ^22.12 || >=23 and a running Chromium-based browser
with remote debugging (Edge/Chrome on port 9222, or 9223 via portproxy).
Related MCP server: Enhanced Browser MCP Server
MCP configuration
Claude Code / Claude Desktop
npm install (recommended):
{
"mcpServers": {
"cdt-smart-snapshot": {
"command": "cdt-smart-snapshot",
"env": {
"CDT_BROWSER_URL": "http://127.0.0.1:9222",
"CDT_SNAPSHOT_DIR": "/tmp/cdt-snapshots"
}
}
}
}From source:
{
"mcpServers": {
"cdt-smart-snapshot": {
"command": "node",
"args": ["/absolute/path/to/cdt-smart-snapshot/build/src/index.js"],
"env": {
"CDT_BROWSER_URL": "http://127.0.0.1:9222",
"CDT_SNAPSHOT_DIR": "/tmp/cdt-snapshots"
}
}
}
}Hermes
mcp_servers:
cdt-smart-snapshot:
command: cdt-smart-snapshot # or: node + build/src/index.js from source
env:
CDT_BROWSER_URL: http://127.0.0.1:9222 # default when browser is local; WSL2: see "Connecting to a browser"
CDT_SNAPSHOT_DIR: /tmp/cdt-snapshots
timeout: 300Prefer CDT_WS_ENDPOINT when you already have a WebSocket debugger URL.
Connecting to a browser
This server does not launch a browser. It connects to a Chromium-based
browser that is already running with remote debugging enabled. What to put in
CDT_BROWSER_URL depends on where that browser runs relative to this server.
1. Start a browser with remote debugging
Pick a browser you already have installed (Edge / Chrome / Chromium):
# macOS / Linux
"/Applications/Google Chrome.app/Contents/MacOS/Google Chrome" \
--remote-debugging-port=9222 --user-data-dir=/tmp/cdt-profile &
# Windows (PowerShell)
& "C:\Program Files\Google\Chrome\Application\chrome.exe" `
--remote-debugging-port=9222 --user-data-dir=C:\temp\cdt-profile
--user-data-diruses a fresh profile so the debugging instance does not clash with your normal browser session. Log into sites inside this window; the server sees that logged-in session.
2. Decide what CDT_BROWSER_URL to use
Where the MCP server runs |
| Notes |
Same machine as the browser (macOS / Linux / Windows native) |
| Default. Nothing to change. |
WSL2 (browser runs on Windows) |
| Needs the portproxy bridge (below). |
Docker container (browser on host) |
| Docker Desktop exposes the host automatically. |
The default http://127.0.0.1:9222 covers the common case; only change it if
the browser is somewhere else.
3. WSL2: the portproxy bridge (browser on Windows)
Chromium's debugging port binds 127.0.0.1 inside Windows. WSL2 is a
separate VM — its own 127.0.0.1 is not Windows', so it cannot reach the
port directly. The standard fix is a netsh portproxy that listens on all
interfaces on 9223 and forwards to Windows' 127.0.0.1:9222:
netsh interface portproxy add v4tov4 listenaddress=0.0.0.0 listenport=9223 \
connectaddress=127.0.0.1 connectport=9222Then find the Windows host IP from WSL and verify:
# From WSL — print the Windows host IP (gateway of the default route)
ip route show default | awk '{print $3}'
# e.g. 172.27.64.1 → CDT_BROWSER_URL=http://172.27.64.1:9223
# Verify the bridge works
curl -s http://<windows-host-ip>:9223/json/versionSecurity: the debugging port is a browser master switch. Keep the portproxy bound to your own machine / trusted network; do not expose
9222on the public internet.
Tools
Tool | Purpose |
| Visible + interactive semantic tree with depth limit and dedupe |
| Added / removed / changed nodes since the last snapshot |
| Write screenshot to disk; returns a file path (no base64) |
| Search the latest snapshot tree by keyword; returns matching uid+path |
| Details for one uid: path, value, checked, rect, css selector |
| uid → unique CSS selector (feed to official server's click/fill) |
| URL/title/readyState/loading + recent console errors & failed reqs |
| Dump the current uid index (explore / debug) |
Query tools (page_search / get_node / element_to_selector) read the uid
index refreshed by every smart_snapshot / snapshot_diff call, so call a
snapshot tool first. If the page navigated since the last snapshot they ask
you to re-snapshot.
Environment
Variable | Default | Meaning |
| (unset) | Prefer WebSocket CDP endpoint when set |
|
| HTTP CDP URL for |
|
| Screenshot output directory |
|
| Default maxDepth |
Benchmark
Measured 2026-08-05 on Edge 151 (Windows) via WSL2 + portproxy 9223. 15 diverse real sites × 3 rounds, official take_snapshot-equivalent (full AX tree, official format) vs. smart_snapshot pipeline. Network idle + retry loading; reduction is stable across rounds (max spread ≤ 6.6pp, 11/15 ≤ 2.3pp).
Per-site reduction (v0.1.6, avg of 3 rounds)
Site | Type | Official chars | Smart chars | Reduction |
Amazon | e-commerce | ~36K | ~2.0K | 94.4% |
CNN | news portal | ~40K | ~3.3K | 91.8% |
social | ~32K | ~3.4K | 89.5% | |
BBC News | news portal | ~27K | ~3.6K | 86.6% |
163.com | CN portal | ~32K | ~5.1K | 84.2% |
JD.com | CN e-commerce | ~11K | ~3.3K | 70.8% |
Gmail | logged-in mail | ~74K | ~24K | 68.0% |
Stack Overflow | Q&A | ~23K | ~8.1K | 64.8% |
YouTube | video | ~2.7K | ~1.4K | 47.0% |
Bilibili | video | ~5.7K | ~3.0K | 47.1% |
Zhihu | CN Q&A | ~2.7K | ~1.8K | 32.5% |
Baidu | search | ~2.0K | ~1.5K | 25.4% |
Wikipedia | long doc | ~578K | ~463K | 19.9% |
GitHub | dev platform | ~4.2K | ~3.4K | 18.2% |
search | ~913 | ~834 | 8.6% |
Measured 2026-08-05 (v0.1.6) on Edge 151 (Windows) via WSL2 + portproxy 9223,
15 sites × 3 complete rounds (45/45 valid). Overall average reduction 56.6%
(avg official tokens 14543 → smart 8795). Raw data: bench/bench-results-3x.json.
v0.1.6 fixes: Baidu/Zhihu went from negative (-10.5% / -13.2% in v0.1.4) to +25.4% / +32.5% — self-labeling controls (link/button/...) now fold their redundant text children, which dominated these label-heavy pages. Bilibili 18.1% → 47.1%. Wikipedia 2.8% → 19.9% (v0.1.5 fix kept: only interactive roles stamped visible on large pages, body text read via
evaluate).
snapshot_diff (incremental, Gmail)
Step | Output |
First call | full tree (~25K chars) |
No-op step | 1 line, 32 chars |
Change step | 8 lines, ~420 chars |
Reading the numbers
High reduction (62–94%): portals / e-commerce / news / social — the page types agents operate on most. Hidden/ads/container nodes are dropped.
Medium (18–48%): video / search / long-doc — nav chains collapsed and redundant text folded; long-doc body text is intentionally kept for the agent to read (read specific sections via
evaluatefor extreme savings).Low (8–10%): GitHub / Google — official interestingOnly already trimmed most junk; the page is small so savings are bounded.
Combined with snapshot_diff, a 30-step agent session on an interactive page consumes roughly 15–20% of the tokens of repeated full take_snapshot calls.
Reproduce: node bench/multi-site-3x.mjs (requires Edge debugging mode on 9222
→ portproxy 9223, set CDT_BROWSER_URL=http://<windows-host-ip>:9223).
Snapshot output
Every snapshot starts with the page root line, e.g.
[RootWebArea] DeepSeek 开放平台. Named images appear as [image] "name"
(Chrome's AX tree reports the role image). These lines were missing before
v0.1.7 — the root was dropped by the visibility pass and named logos were
filtered out — so any snapshot output you see is from v0.1.7+ unless stated.
DOM query tools (v0.2.x)
get_node / element_to_selector read live DOM state behind a uid. v0.2.0
had a bug that made every DOM lookup fail (CDP objectId bound to the wrong
session); it is fixed in v0.2.1. If you're on 0.2.0, upgrade:
npm install -g cdt-smart-snapshot@latestAfter upgrading, element_to_selector(uid) returns a unique CSS selector you
can feed straight to the official chrome-devtools-mcp click / fill, and
get_node(uid) shows the real element state (value, checked, rect, selector).
Development
npm run test
npm run typecheck
npm run check-formatLicense
Apache-2.0
Available Tools
8 toolselement_to_selectorA
Return a unique CSS selector for a snapshot uid (for chrome-devtools-mcp click/fill). Requires smart_snapshot or snapshot_diff first.
| Name | Required | Description | Default |
|---|---|---|---|
| uid | Yes | Stable uid from the snapshot output. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description bears the full transparency burden. It discloses the dependency on a prior snapshot/diff and defines the output as a unique CSS selector. It does not cover failure modes or exact return type, but these are minor for a simple conversion tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single sentence that leads with the core action and resource, then provides the prerequisite. Every word is necessary and there is no redundant information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a single-parameter tool with no output schema, it is mostly complete: it states what is returned, the required prior step, and the automation use case. The main gap is that it doesn't mention the return format (e.g., string) or error behavior, but these are not critical for the tool's intended use.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%; the only parameter 'uid' is already described as 'Stable uid from the snapshot output.' The tool description merely reinforces 'snapshot uid' without adding new meaning, so it stays at the baseline of 3 with no additional semantic contribution.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb 'Return' and clearly defines the resource: a unique CSS selector for a snapshot uid. It also names the intended downstream use (chrome-devtools-mcp click/fill), which distinguishes it from sibling tools like get_node or snapshot_index that likely return node data rather than selectors.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly states a precondition (requires smart_snapshot or snapshot_diff first) and identifies the use case (for click/fill). It does not explicitly name alternatives or exclusions, but the context makes it clear when to use this tool, which is adequate for this utility.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_nodeA
Return role, path, DOM geometry, and CSS selector for one snapshot uid. Requires a prior smart_snapshot or snapshot_diff.
| Name | Required | Description | Default |
|---|---|---|---|
| uid | Yes | Stable uid from the snapshot output. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries full burden. It discloses that it returns specific node data and requires a prior snapshot, but it does not mention error behavior (e.g., invalid uid) or explicitly state that it has no side effects.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
One sentence that front-loads the action and outputs, with no filler. Every clause adds value, and the prerequisite is clearly stated.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Simple tool with one parameter and no output schema. Description covers purpose, exact return items, and prerequisite. It lacks error/no-result behavior, but given the simplicity, this is adequate and fits well within the snapshot workflow indicated by siblings.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Input schema has 100% coverage with 'Stable uid from the snapshot output.' The tool description reinforces this by saying 'one snapshot uid' and 'Requires prior smart_snapshot or snapshot_diff,' but adds no new syntax or format details. Baseline 3 for full schema coverage.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses the specific verb 'Return' and enumerates exact outputs (role, path, DOM geometry, CSS selector) for a single snapshot uid. This clearly distinguishes it from siblings like smart_snapshot or snapshot_diff which create snapshots/diffs.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly states a prerequisite: 'Requires a prior smart_snapshot or snapshot_diff.' This gives clear context for when the tool can be used, but it does not mention alternatives or exclusion cases.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
page_searchA
Search the most recent smart_snapshot tree for a keyword. Returns matching uids with role, name, and path. Call smart_snapshot or snapshot_diff first.
| Name | Required | Description | Default |
|---|---|---|---|
| keyword | Yes | Case-insensitive substring to match against name, value, or path. | |
| maxResults | No | Maximum matches to return (1–100). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the transparency burden. It discloses the tool reads the most recent snapshot and returns specific fields (role, name, path), and explains the dependency on prior calls. However, it doesn't explicitly state side-effect safety (though 'search' implies read-only) or behavior when no snapshot exists.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences, each serving a purpose: stating the action and target, describing return fields, and giving a prerequisite. No redundant information or filler.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers the tool's purpose, dependency, and return shape, which is especially useful given there is no output schema. It lacks error-case handling, but for a simple search tool with well-documented parameters, it is sufficiently complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema already provides full descriptions for both parameters (100% coverage), so the description doesn't need to add parameter details. It neither repeats nor contradicts the schema, but adds no extra semantic value beyond the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('Search') and resource ('most recent smart_snapshot tree'), making the tool's function clear. It distinguishes itself from sibling tools like snapshot_index or get_node by focusing on keyword search over a snapshot.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly states to call smart_snapshot or snapshot_diff first, establishing a clear prerequisite and usage order. It does not name alternative tools for other scenarios, but the guidance is sufficient for when to use this tool.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
page_statusA
Report current page URL, title, readyState, loading flag, and recent console errors, page exceptions, and failed network requests.
| Name | Required | Description | Default |
|---|---|---|---|
| clear | No | When true, clear diagnostic buffers after returning this status. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the transparency burden. It lists the reported data but omits side effects (e.g., clearing diagnostic buffers when 'clear' is true) and does not define the scope of 'recent' errors. This is a moderate level of disclosure.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, direct sentence that front-loads the action ('Report') and concisely lists all included data. No redundant words or filler.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description lists the data categories but does not specify the output format or the structure of error/exception details. With no output schema and no annotations, this creates ambiguity about the return value, making the description only partially complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The single parameter 'clear' is fully documented in the schema with a clear explanation (100% coverage). The description adds no additional parameter semantics, so the baseline score of 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly identifies the tool's purpose with a specific verb ('Report') and enumerates exact data points (URL, title, readyState, loading flag, console errors, exceptions, network requests). This distinguishes it from sibling snapshot/search tools, which focus on DOM or visual state.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
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 or how it fits into a workflow. It simply states what it reports, leaving the agent to infer use cases.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
screenshot_to_diskA
Takes a screenshot, saves it to disk, and returns the file path. Saves ~3000-5000 tokens per screenshot compared to returning base64. Read the file with read_file if you need to inspect it.
| Name | Required | Description | Default |
|---|---|---|---|
| format | No | Screenshot format. | png |
| quality | No | JPEG quality (ignored for PNG). | |
| fullPage | No | If true, capture the full scrollable page. | |
| directory | No | Output directory override. Defaults to config screenshotDir (system temp). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of behavioral disclosure. It mentions saving to disk and returning a file path, which is core behavior, but does not cover potential side effects (e.g., disk cleanup, overwriting, permissions) or error conditions. The token-saving benefit is useful context but not a behavioral trait in the safety sense.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is exactly two sentences. The first sentence states the primary purpose, and the second adds a practical benefit and follow-up action. It is front-loaded, efficient, and contains no irrelevant information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple tool with 4 optional parameters and no output schema, the description covers the main outcome (saves to disk, returns path) and gives a key optimization tip. It lacks explicit differentiation from sibling tools and does not address potential errors or edge cases, but the core functionality is adequately described.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so baseline is 3. The description does not elaborate on parameter specifics, but it implies the tool produces a screenshot file; the schema already documents all parameters (format, quality, fullPage, directory) with individual descriptions. No additional semantic value is added.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's action ('Takes a screenshot, saves it to disk, and returns the file path') with a specific verb and resource. It does not explicitly mention sibling tools, but the focus on saving to disk and returning a file path differentiates it from common alternative approaches like returning base64.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides usage context by highlighting token savings ('Saves ~3000-5000 tokens per screenshot compared to returning base64') and instructs how to inspect the file ('Read the file with read_file if you need to inspect it'). It gives an implicit alternative (returning base64) but does not explicitly name or exclude sibling tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
smart_snapshotA
Returns a token-efficient semantic snapshot of the current page: only visible, interactive and meaningful nodes, with depth limiting and deduplication. Use this instead of take_snapshot to save context.
| Name | Required | Description | Default |
|---|---|---|---|
| verbose | No | If true, include container/static nodes too. Default false (interactive + meaningful text only). | |
| maxDepth | No | Maximum tree depth. Deeper subtrees are collapsed into a summary line. | |
| includeHidden | No | If true, include offscreen/hidden nodes (useful for debugging). Default false. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It transparently explains the filtering criteria (visible, interactive, meaningful), depth limiting, and deduplication behavior. It does not explicitly state whether the tool is read-only, but as a 'snapshot' this is implied. The inclusion of includeHidden and verbose parameters further clarifies default behavior, which the schema mirrors.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is only two sentences and front-loads the primary action and outcome. Every piece of information is useful: what the tool returns, its key behaviors (filtering, depth limiting, deduplication), and when to use it. No fluff or repetition.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's moderate complexity (3 optional params, no output schema), the description fully captures the purpose, filtering behavior, and usage guidance. It also points to take_snapshot as the alternative, which aids selection. The lack of output schema is compensated by the description of what the snapshot consists of ('nodes'). The tool is well understood from this alone.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
All three parameters are fully described in the schema (100% coverage), so the baseline is 3. The description adds semantic context by framing the tool as 'token-efficient' and 'semantic', which explains the purpose of verbose (disabled by default to save tokens) and maxDepth (limit depth to avoid huge dumps). This layer of meaning goes beyond the individual parameter comments.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool returns a token-efficient semantic snapshot of the current page, filtering to visible/interactive/meaningful nodes with depth limiting and deduplication. This specific verb+resource+output distinguishes it from the sibling tools (snapshot_diff, screenshot_to_disk) and explicitly contrasts with take_snapshot.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The second sentence 'Use this instead of take_snapshot to save context' gives an explicit, actionable usage directive. This directly tells the agent when to choose this tool over an alternative, satisfying the dimension fully.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
snapshot_diffA
Returns only the changes between the current page state and the previous smart_snapshot call. Added/removed/changed nodes with a few lines of context. Use this on every step after the first to consume minimal tokens.
| Name | Required | Description | Default |
|---|---|---|---|
| verbose | No | Same as smart_snapshot. | |
| maxDepth | No | Same as smart_snapshot. | |
| includeHidden | No | Same as smart_snapshot. |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of disclosure. It describes the diff-only output, adds context about added/removed/changed nodes, and mentions token efficiency. It does not mention error handling for missing previous snapshot, but the dependency is implied.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two sentences, front-loaded with the core purpose and followed by a usage tip. Every word earns its place, with no redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with three optional parameters and no output schema, the description adequately explains purpose, usage, and return type. It lacks explicit failure behavior if no previous snapshot exists, but overall is sufficient for selection and invocation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema descriptions cover all three parameters, referencing smart_snapshot, giving 100% coverage. The tool description adds no extra detail about verbose, maxDepth, or includeHidden, so it meets the baseline for high schema coverage.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states it returns only changes between the current page state and the previous smart_snapshot call, which is a specific verb and resource. This distinguishes it from sibling tools like smart_snapshot (full snapshot) and page_status.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly instructs to use this tool on every step after the first to minimize token consumption, implying the first step should use smart_snapshot. This provides clear when-to-use guidance and names the alternative.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
snapshot_indexA
List uids from the most recent snapshot (role, name, path). Useful before page_search or get_node. Requires smart_snapshot or snapshot_diff first.
| Name | Required | Description | Default |
|---|---|---|---|
| maxResults | No | Maximum rows to list (1–500). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries full burden. It discloses the dependency on prior snapshot creation and the columns returned, but does not explicitly state read-only behavior, return format, or potential side effects. The prerequisite and column detail add some value beyond a bare list.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences, front-loaded with the action and resource. The first sentence defines the output, and the second gives usage and prerequisites. No redundant or filler content; every sentence earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's low complexity (one optional parameter, no output schema), the description adequately covers purpose, columns, usage context, and a prerequisite. It does not explicitly describe the return format, but for a simple uid listing this is largely self-evident and the dependency guidance provides essential context.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% for the single parameter maxResults, which includes description, default, min, and max. The description adds no additional information about this parameter, so the schema already does the heavy lifting, resulting in the baseline score of 3.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Description states 'List uids from the most recent snapshot' with specific columns (role, name, path), clearly identifying the resource and action. It distinguishes itself from siblings like snapshot_diff and page_search by focusing on uid listing from a snapshot.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Provides explicit usage context ('Useful before page_search or get_node') and a prerequisite ('Requires smart_snapshot or snapshot_diff first'). However, it does not mention when not to use or name alternatives, so it falls short of a 5.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
TDQS
Each tool targets a distinct aspect of snapshot management: capture, diff, status, screenshot, search, node details, selector generation, and indexing. There is no overlap that would cause an agent to misselect.
All names use snake_case and are descriptive, but the pattern is mixed: some are verb-led (get_node), some noun-led (page_status), and some use prepositions (screenshot_to_disk, element_to_selector). This inconsistency makes the set less predictable than a uniform verb_noun convention.
8 tools is well-scoped for a specialized snapshot server. Each tool serves a clear purpose with no redundancy, and the count is neither too thin nor too heavy.
The server covers the full snapshot lifecycle: capture (smart_snapshot), diff (snapshot_diff), inspection (snapshot_index, page_search, get_node), and action support (screenshot_to_disk, element_to_selector). No significant gaps exist for its stated purpose.
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