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query_debug

Diagnose why a CSS selector fails to match. Get matched count, sample matches, DOM summary, and actionable hints for selector_miss, thin_shell, or embedded_json.

Instructions

Diagnose why a CSS selector did or did not match. Returns matched_count, sample matches, DOM summary counts, selector hints (top tags/classes/data attrs/ids), and actionable hints for selector_miss, thin_shell, or embedded_json. Use this when query() returns [] and you need to distinguish a bad selector from an empty/browser-rendered DOM.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
limitNoMax sample matches to return (default 10, max 50)
selectorYesCSS selector to test
Behavior4/5

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

No annotations are provided, so the description carries the burden. It discloses return fields and diagnostic hints (selector_miss, thin_shell, embedded_json). It does not mention any side effects or limitations, but is generally transparent about its diagnostic nature.

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

Conciseness5/5

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

Two sentences efficiently convey purpose, return data, and usage context. No redundant or wasted words.

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 debug tool with no output schema, the description adequately lists return fields and explains when to use it. It provides enough context for an AI agent to select and invoke correctly.

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?

Input schema has 100% description coverage. The description does not add significant meaning beyond the schema. 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 clearly states the tool diagnoses CSS selector matching, lists specific return fields, and explicitly mentions the use case when query() returns []. It effectively distinguishes itself from the sibling tool 'query'.

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

Usage Guidelines4/5

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

The description explicitly instructs to use this tool when query() returns [], providing a clear usage trigger. While it lacks explicit when-not-to-use instructions, the context strongly implies the alternative is the query() tool.

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

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