chrome-devtools-mcp-mux

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

Annotations indicate readOnlyHint=false, implying a write operation, which aligns with 'Stop' as a mutation. The description adds minimal behavioral context beyond this, mentioning it saves trace data to a file path but not detailing effects like trace termination, potential errors, or interaction with other performance tools. With annotations covering the safety profile, it earns a baseline score for adding some value without contradiction.

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, direct sentence that front-loads the core action and resource without unnecessary words. It efficiently communicates the essential purpose, making it highly concise and well-structured for quick understanding.

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 one parameter with full schema coverage, no output schema, and annotations providing basic safety info, the description is minimally adequate. However, it lacks details on prerequisites (e.g., requires an active trace), error handling, or output implications, leaving gaps for a mutation tool in a performance context with sibling tools.

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%, with the parameter 'filePath' fully documented in the schema. The description does not add any semantic details beyond what the schema provides (e.g., it doesn't explain default behavior if omitted or file format implications), so it meets the baseline for high schema coverage without extra value.

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 ('Stop') and the resource ('active performance trace recording on the selected webpage'), making the purpose immediately understandable. However, it doesn't explicitly differentiate from sibling tools like 'performance_start_trace' or 'performance_analyze_insight' beyond the obvious verb difference, which keeps it from a perfect score.

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, prerequisites (e.g., must have an active trace started with 'performance_start_trace'), or what happens if no trace is active. It lacks explicit when/when-not instructions or named alternatives, leaving usage context implied at best.

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