memory_stats

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered and the bar is lower. The description adds that this is a diagnostic/inspection surface rather than a mutation, but with an output schema present it needn't restate return structure, and it offers no extra behavioral context (refresh cadence, cost, scoping) beyond the metric names.

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 metric list front-loaded and a single actionable usage clause following. No filler sentences; every clause 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 zero-parameter tool with a published output schema and rich annotations, the description supplies enough context to call it correctly and know why. It could be slightly more complete by hinting at what to do with a bad reading (which sibling to turn to), but nothing required for invocation is missing.

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 there are no parameter semantics to explain; per the rubric this is the baseline 4. Nothing in the description misleads about inputs.

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 resource (the memory bank's "vital signs") and enumerates the concrete metrics returned: store occupancy vs capacity, hit rates, true-drop count, and totals. This clearly sets it apart from the read/write memory siblings, though it never names a sibling directly to sharpen the contrast.

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 to gauge how much has been remembered or to diagnose why retrieval feels off" gives two explicit usage contexts, which is strong when-to-use guidance. It stops short of stating when-not to use it or naming an alternative (e.g. memory_search for retrieval debugging), so it isn't a full 5.

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