Extract an element's innerText from a web page by selector, snapshot ref, or tab, with optional truncation to a maximum character count.
innerText of an element, truncated to max characters.
| Name | Required | Description | Default |
|---|---|---|---|
| max | No | ||
| ref | No | ref from snapshot, e.g. e3 | |
| tab | No | tab id, defaults to current | |
| selector | No | CSS selector | |
| request_timeout | No | Outer page request deadline in milliseconds; defaults to at least 30000 |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, but it does usefully disclose truncation to max characters — context the schema does not provide since the max property has no description. It omits what happens when neither ref nor selector is supplied, which element wins on multiple matches, and failure behavior, leaving significant gaps for an unannotated 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?
A single front-loaded sentence with no filler, and the truncation caveat is attached directly to the resource. The terseness borders on under-specification rather than excess, but nothing written is wasteful.
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?
Five optional parameters, no annotations, and no output schema mean the description should explain element targeting and defaults, yet it only covers what innerText returns and that it truncates. An agent must guess how ref, selector, and tab interact before it can call this correctly.
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 80%, so most parameters are already documented, and the description compensates for the one gap by explaining that max truncates output. It says nothing about ref/selector precedence or tab targeting beyond what the schema states, so this is the baseline.
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 names a specific extraction action and resource ("innerText of an element") plus its truncation behavior, so an agent knows exactly what is returned. It does not distinguish itself from sibling readers like html, attr, or eval, which would be needed for a 5.
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?
There is no statement of when to use this instead of html, attr, snapshot, or eval, and no guidance on the ref-vs-selector choice that determines which element is read. Usage must be inferred entirely from the tool name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.