performance_start_trace

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

The description lacks behavioral details beyond the annotations and schema. For instance, it does not mention that tracing might affect page performance, that a page must be loaded, or that the trace should be stopped with the sibling tool. The schema provides more behavioral info on reload and autoStop, but the description adds little.

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 sentence that efficiently conveys the tool's purpose and use case. It is concise and front-loaded with the action, with no wasted words.

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 tool's simplicity (3 params, no output schema), the description covers the basic purpose and use. However, it omits important context such as the need to stop the trace afterward and the nature of the output file (though mentioned in schema). It is adequate but not thorough.

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?

All parameters have descriptions in the input schema (100% coverage). The tool description does not add any additional meaning beyond what the schema already provides, so a 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 tool starts a performance trace on the selected webpage to find frontend performance issues and Core Web Vitals. The purpose is clear, but it does not explicitly differentiate from sibling tools like performance_stop_trace, though the naming implies the relationship.

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 suggests using the tool to find performance issues, providing usage context. However, it does not specify when not to use it or mention alternatives, such as lighthouse_audit for broader audits.

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