Web Vitals Time Series

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds the context that the data is time-series oriented around Core Web Vitals, which is useful, but it does not disclose behavioral details such as output shape, metric list, or time range handling.

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 that communicates the core action, metric domain, data format, and purpose without any filler. Every word contributes value.

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?

With no output schema, the description should partially compensate by explaining what the returned time-series contains or how metrics are presented, but it only says 'performance metrics' in general. The parameter schema is complete, so invoking the tool is feasible, but an agent lacks detail on expected return values and exact metric coverage.

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 fully documents all 8 parameters including bucket, dates, and filters. The description does not add meaning beyond the schema, which matches the baseline expectation. No additional parameter nuance or examples are needed beyond what is already provided.

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 states a specific verb and resource: 'Get Core Web Vitals performance metrics as time-series data.' This clearly identifies the tool's purpose and differentiates it from generic list or overview tools. However, it does not explicitly distinguish itself from sibling tools like rybbit_get_performance or rybbit_get_overview_timeseries, so the differentiation is left to the agent.

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 phrase 'for trend analysis' implies the tool is intended for analyzing performance over time, providing some usage context. There is no explicit guidance on when to choose this tool over alternatives, nor any mention of exclusions or when not to use it.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.