chrome-devtools-mcp-mux

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

The description adds some behavioral context beyond annotations - it explains the default URL behavior ('Use project URL if not specified otherwise') and implies page creation. However, annotations already declare readOnlyHint=false, so the agent knows this performs mutations. The description doesn't add significant behavioral traits like what happens if the URL fails to load, whether the page becomes active, or any rate limits. With annotations covering the mutation aspect, a 3 is appropriate.

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 perfectly concise with two sentences that each earn their place: the first states the core functionality, the second provides important default behavior. It's front-loaded with the main purpose and wastes no words. This is an excellent example of efficient documentation.

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 this is a mutation tool (readOnlyHint=false) with no output schema, the description provides adequate context for basic usage. It explains what the tool does and includes important default behavior. However, for a tool that creates new browser pages, additional context about what constitutes success/failure, whether the page becomes active, or any side effects would be helpful but aren't critical given the straightforward nature of the operation.

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 fully documents all three parameters (url, background, timeout). The description doesn't add any parameter-specific information beyond what's in the schema - it mentions URL generally but doesn't provide additional syntax, format, or usage details. Baseline 3 is correct when the schema does all the parameter documentation work.

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 specific action ('Open a new tab and load a URL') and resource ('page'), distinguishing it from siblings like 'navigate_page' (which navigates existing pages) and 'select_page' (which selects among existing pages). It explicitly mentions the tool's unique capability to create new tabs rather than work with existing ones.

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 clear context about when to use this tool ('Open a new tab and load a URL') and includes a usage rule ('Use project URL if not specified otherwise'), but doesn't explicitly state when NOT to use it or name specific alternatives. It implies this is for creating new pages rather than navigating existing ones, but doesn't explicitly contrast with 'navigate_page' or other page-related tools.

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