memory_stats

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description's 'Safe to call' aligns with that without adding new safety info. The description adds context about the outcome (size category) but does not describe return format, granularity, or edge cases. Given the annotations cover the safety profile, 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 a single, tightly written sentence that leads with the core purpose and then adds the key usage guidance. There is zero wasted wording, and the most important information (what it does and when to use it) is front-loaded.

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 simple tool with one optional parameter and no output schema, the description covers the essential points: what it provides (high-level stats) and a canonical use case (first call). It does not explicitly differentiate from memory_data_inventory or memory_capabilities, but the size-assessment focus is enough for most agents to select it correctly. A mention of output shape or a contrast with siblings would make it more complete.

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 input schema fully documents the privacy_mode parameter with a detailed description covering all enum values and their behavior. The tool description itself does not mention the parameter, but the schema provides 100% coverage, so the baseline of 3 applies. No additional meaning is added by the description.

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 states the tool provides 'high-level stats about the local memory store' and clarifies its purpose to gauge store size ('empty, small, or large'). This is clear and specific, though it lacks an explicit verb like 'retrieve' or 'get'. It does not explicitly contrast with siblings like memory_data_inventory or memory_capabilities, which could be confused, but the size-gauge focus gives a distinct angle.

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 when-to-use instruction: 'Safe to call first on every session to gauge whether the store is empty, small, or large.' This provides a concrete use case. It does not mention when not to use it or name alternatives, but the guidance is actionable and distinguishes it as an initial assessment tool.

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