system_stats_digest

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

Annotations already cover the read-only, non-destructive safety profile, so the bar is lower, and the description adds real behavioral context beyond them: daily (UTC) storage granularity and the consequence that the 'traffic by new users' metric snaps to whole days at range edges. It omits return shape, but no output schema exists so that duty is unclear.

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?

Front-loaded with the verb and resource, then the returned metrics, then the caveat. Every sentence carries information, though the daily-granularity caveat is a touch long-winded for a two-parameter tool.

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 read-only, two-parameter stats tool with full schema coverage and no output schema, the description covers inputs, outputs, and the one non-obvious behavioral quirk. The remaining gap is sibling differentiation among the several system_stats_* tools.

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?

Schema description coverage is 100% and both parameters already document ISO 8601 format and inclusive/exclusive semantics; '[start, end)' in the description merely restates that. Baseline 3, with no added syntax or format detail beyond the 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?

States a specific verb and resource ('Get Stats Digest') and enumerates exactly which aggregates it returns (created/expired users, total traffic, traffic by new users, new HWID devices). Clear on its own, but it never distinguishes itself from close siblings like system_stats, system_stats_recap, or system_bandwidth_stats, leaving overlap ambiguous.

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?

Usage is only implied: the metric list hints at when an agent would want this (a digest of user/traffic/HWID activity over a range), but there is no explicit when-to-use, no prerequisites, and no routing to/away from the many system_stats_* siblings. Adequate but leaves the agent to infer.

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