Scroll the page up or down by a number of viewport-heights.
| Name | Required | Description | Default |
|---|---|---|---|
| amount | No | Scroll amount in viewport-heights (default: 3) | |
| direction | No | Scroll direction: "up" or "down" (default: down) | down |
| session_id | Yes | Session ID |
Changes observed during successful MCP inspections. Dates show when Glama detected each change.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only provide a title, so the description carries the behavioral burden. It discloses the core behavior and units, but does not mention side effects, session requirements, relative scrolling behavior, or what happens on invalid input.
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?
The description is a single, front-loaded sentence with no filler. Every word contributes to the meaning, and it remains highly scannable for an agent.
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 simple scroll tool with full schema coverage, the description covers the essential operation. It does not describe return values or explicitly state that the scroll applies to the session associated with session_id, but the low complexity and rich schema make this acceptable.
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?
The input schema has 100% parameter coverage, including descriptions for amount, direction, and session_id. The description adds no new parameter semantics beyond what the schema already states, so the baseline score of 3 is appropriate.
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 clearly states the action ('Scroll the page up or down') and the resource/scope ('by a number of viewport-heights'). This is specific enough to distinguish session_scroll from sibling tools like session_navigate, session_click, or session_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?
The description provides no guidance on when to use this tool versus alternatives, no prerequisites such as requiring an active session, and no exclusions. It only describes the operation itself, leaving usage decisions entirely to the agent.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Most tools have distinct purposes, but there's overlap between session_click/click and session_eval/eval. Descriptions clarify that session_* tools operate on persistent sessions while the others are one-off, so ambiguity is low.
The session_* prefix is consistently used for session-related tools (17 of 23), while the remaining tools (cache, click, download, eval, fetch, search) are single-word lowercase verbs. This is a clear pattern, though not strictly verb_noun.
23 tools is above the typical 3-15 range but reasonable for a browser automation server that needs both one-off and session-based operations. The count is justified by the breadth of features, though it's slightly heavy.
The surface covers all major browser automation needs: navigation, clicking, typing, scrolling, screenshot, state inspection, console/network logs, cookies/storage management, JavaScript eval, waiting, and even session export. No obvious gaps for the stated purpose.