Open a target URL in a headless browser session to start page interaction, accessibility tree extraction, or status checks; optionally specify a session ID.
Navigate headless browser session to target URL.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | Destination web address (e.g., 'https://example.com'). | |
| session_id | No | Session identifier (default: 'default'). |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It discloses only that the session is 'headless,' but says nothing about whether navigation blocks until load, timeout behavior, handling of failed/redirected URLs, or whether it reuses the 'default' session. For a state-changing browser action this is a substantial 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 tight sentence with the action front-loaded and zero filler. It is efficient, though its brevity borders on under-specification rather than optimal conciseness.
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 tool is low-complexity with only two parameters, but there are no annotations and no output schema, so the description should at minimum explain what navigation returns or guarantees (e.g., load completion, status). None of that behavioral context is present.
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 both the url and session_id parameters are already fully documented in the schema (including the default value for session_id). The description adds no syntax, format, or constraint beyond what the schema provides, so the baseline 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?
States a specific verb ('Navigate') and resource ('headless browser session to target URL'), making the action unambiguous. However, it offers no differentiation from siblings like get_page_status or extract_clean_text, which also act on the same browser session.
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 when-to-use guidance, no prerequisites (e.g., must a session exist or be created first?), and no mention of alternatives among the sibling browser tools. The agent must infer that navigation precedes extraction/click tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.