List running browsers

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

Annotations already declare readOnlyHint=true, so the read-only nature is known. The description adds the specific output fields (ws.puppeteer, ws.selenium, debug_port), which is useful context that goes beyond the raw annotation. It does not promise additional behavior, and there is no 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, well-structured sentence that is front-loaded with the action ('List currently running browsers') and immediately provides the key output details. No filler words; every part earns its place.

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?

For a no-parameter, read-only list tool with no output schema, this description is fully sufficient. It states what is listed and the important fields returned. There are no hidden parameters, side effects, or complex preconditions, so no additional context is needed.

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?

The tool has zero parameters, so schema coverage is 100% and there is nothing to document. The description does not need to explain parameter syntax, and the baseline of 4 applies since no parameters exist.

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's function: 'List currently running browsers' and specifies exactly what information is returned (automation endpoints ws.puppeteer / ws.selenium / debug_port). It uses a specific verb and resource, and is distinct from sibling tools like list_profiles or open_browser.

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 gives a clear context for when to use this tool: when you need to see which browsers are currently running and their automation endpoints. It does not explicitly name alternatives or exclusions, but the purpose is unambiguous enough to guide selection. Sibling tools like list_profiles serve a different function, implying this is the go-to for running browser instances.

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