Lists the browser tabs served by a CDP port and reports which tab a call would select. Use target_url on other browser calls to pin the page under test when a port has multiple tabs.
List the page tabs one CDP port serves and report which one a call would choose. Pass target_url on other browser calls to pin the page under test when a port holds more than one tab.
| Name | Required | Description | Default |
|---|---|---|---|
| port | No | ||
| target_url | No |
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. It usefully discloses that the tool both enumerates targets and reveals the default selection a later call would make, implying a read-only inspection tool, but it never states what happens if port is omitted (it is optional) or what the returned tab listing looks like.
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, zero waste, with the core function front-loaded and the follow-on guidance second. Nothing repeats the schema or title.
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 two-optional-parameter discovery tool with no annotations and no output schema, the agent still lacks the default port behavior, the shape of the returned tab list, and error conditions for an invalid or unreachable port. It is adequate to attempt a call but not to interpret the result confidently.
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 0%, so the description must explain both parameters. It meaningfully ties `port` to a CDP port and explains `target_url` as the pinning selector for multi-tab ports, but leaves `port`'s optionality/default behavior and the matching semantics of target_url (exact URL vs. substring) undefined.
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?
States a specific verb and resource: 'List the page tabs one CDP port serves and report which one a call would choose.' The second sentence implicitly separates it from the sibling browser action tools (observe/click/fill/scroll) by framing it as the target-discovery step that feeds target_url into those calls.
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?
Gives a clear conditional: use target_url on other browser calls 'when a port holds more than one tab,' which tells the agent both why to call this tool and what to do with its output. It stops short of explicit when-not guidance or naming the sibling tools it complements.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.