Retrieve RUM page view performance metrics for a specified time range, with optional query filters and selectable metrics, to analyze load and rendering performance.
Get page (view) performance metrics from RUM data
| Name | Required | Description | Default |
|---|---|---|---|
| to | Yes | End time in epoch seconds | |
| from | Yes | Start time in epoch seconds | |
| query | No | Optional query filter for RUM search | * |
| metricNames | No | Array of metric names to retrieve |
Changes observed during successful MCP inspections.
v1.8.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries full burden. It states it 'gets' metrics, implying a read operation, but doesn't disclose behavioral traits such as authentication needs, rate limits, pagination, error handling, or what the return format looks like (e.g., structured data, time-series). This is a significant gap for a tool with no annotation coverage.
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, efficient sentence that directly states the tool's purpose without unnecessary words. It's appropriately sized and front-loaded, with zero waste.
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?
Given the complexity (4 parameters, no annotations, no output schema), the description is incomplete. It lacks information on behavioral traits, usage context, and output format, which are crucial for an agent to invoke this tool correctly. The high schema coverage doesn't compensate for these gaps.
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 the schema already documents all parameters thoroughly. The description adds no additional meaning beyond what's in the schema (e.g., it doesn't explain what 'RUM search' entails or provide examples for 'metricNames'). Baseline 3 is appropriate as the schema does the heavy lifting.
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 verb 'Get' and the resource 'page (view) performance metrics from RUM data', making the purpose evident. It distinguishes from some siblings like 'get_rum_applications' or 'get_rum_events' by specifying 'page performance metrics', but could be more explicit about how it differs from 'get_rum_page_waterfall'.
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 guidance is provided on when to use this tool versus alternatives. It doesn't mention prerequisites, context, or compare with siblings like 'get_rum_events' or 'query_metrics', leaving the agent to infer usage based on naming alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.