List the DevTools panels available for a tab

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

readOnlyHint=true already establishes the safety profile, and the description usefully confirms that the output pairs panel names with ids. However, the second sentence is internal implementation trivia (loader path, module id, exported symbol) that discloses nothing an agent needs about the tool's runtime behavior, and there is no mention of return shape or failure modes.

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 first sentence is well-structured and front-loaded with the actionable content. The trailing 'MEASURED:' note on loader internals is off-topic for a caller and adds length without helping selection or invocation.

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 has to say what comes back, and it does: the list of panel identifiers together with the id usable with browser_devtools_open. Only the exact return structure (field names, ordering) is left unspecified.

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 takes zero parameters, so parameter semantics is trivially satisfied and the baseline of 4 applies. Nothing about arguments needs documenting beyond the empty schema.

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?

Specific verb ('List') plus specific resource ('Developer Tools panels this Firefox exposes'), and it enumerates the panel names so the agent knows the output domain. It also distinguishes itself from siblings by naming browser_devtools_open as the consumer of the returned ids.

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 ties usage to a concrete next step: the returned ids are 'the id you can pass to browser_devtools_open', which tells the agent when to reach for this tool before opening a panel. It stops short of explicit when-not conditions or naming browser_devtools_close as an alternative.

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