Report process memory usage

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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real value beyond that by disclosing the shape of the data ('resident / residentUnique / heapAllocated are properties (not methods)' and that getReports() exists for a fuller breakdown), which is exactly the kind of implementation detail that prevents misuse.

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?

Two tight sentences with the core action front-loaded and the usage cue second. The 'MEASURED:' label is slightly jargon-heavy but it efficiently flags the property-vs-method caveat.

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 carries the burden of indicating what comes back, and it names the three key properties plus getReports(). It doesn't describe units (bytes vs MB) or the overall response envelope, so it is strong but not exhaustive.

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 and the empty schema is fully described, so there is nothing for the description to compensate for. Baseline 4 applies.

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?

States a specific verb and resource ('Read live memory figures from nsIMemoryReporterManager') and names the concrete values exposed, which separates it cleanly from siblings like browser_get_cache_usage or browser_get_tab_processes. It stops short of explicitly contrasting those siblings, so it lands just under a 5.

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?

"Use this when a page feels heavy and you want numbers rather than guesses" gives a clear situational trigger. It does not mention when-not-to-use or point at alternative memory/diagnostic tools, which keeps it at 4 rather than 5.

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