cdp_keyPress a key or key combination in a selected browser tab via CDP to trigger page actions, shortcuts, or form submissions.
Press a key or combination (e.g. Enter, Control+A, Escape).
| Name | Required | Description | Default |
|---|---|---|---|
| tab | No | Tab index from cdp_tabs to act on. | |
| url | No | Pick the tab whose URL contains this substring. | |
| port | No | CDP debug port (default 9222). | |
| combo | Yes | Key or chord to press, e.g. Enter or Control+A | Enter |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already flag destructiveHint=true / readOnlyHint=false, so the safety profile is partially covered. The description adds nothing beyond that: it does not say which element receives the key, whether the target tab is focused or brought forward, what URL/tab/port selection does, or what happens if no element has focus. For a keystroke tool marked destructive, that is a meaningful gap.
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 zero waste. It is under-specified rather than padded, so it loses a point only relative to how much behavior is left unexplained for a 4-parameter tool.
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?
No output schema exists and the description does not compensate: it omits target selection, focus requirements, and any indication of success or failure. Combined with destructive annotations on a keystroke primitive, an agent lacks enough context to invoke this safely.
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 tab, url, port, and combo are already documented in the schema, and the description's combo examples only restate the schema. Baseline 3 is appropriate; the description adds no targeting or precedence semantics (e.g. tab vs url).
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 concrete verb and resource ('Press a key or combination') and gives representative combos, so the agent knows this dispatches a keystroke rather than typing text. It does not, however, contrast itself with the near-siblings cdp_type, desktop_type, or desktop_shortcut, which all dispatch input.
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?
No when-to-use, when-not-to-use, or alternative is given. An agent cannot tell from the description whether this targets a browser tab (via tab/url/port) or the currently focused element, nor when to prefer cdp_type or desktop_shortcut.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.