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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds useful behavioral context—history starting October 3, 2026, dataset coverage variability, and the 'followed, gap-free, full tapes only' filter—but these constraints are cryptic and unexplained.

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 compact and front-loads the day scope, but packs multiple opaque metrics and filter conditions into dense clauses ('positive/doubled 30-minute changes', 'followed, gap-free, full tapes only') without explanation. Conciseness is achieved at the cost of comprehensibility.

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 must convey what the tool returns; it names several metrics but does not explain their format or meaning. History and coverage notes are helpful, but key domain terms remain undefined for an uninitiated agent.

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 coverage is 100% and the single `day` parameter is fully documented in the schema, including its default. The description adds no additional meaning about the parameter beyond restating UTC-day semantics, so baseline 3 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?

The description indicates the resource (statistics for a single UTC day: graduate counts, 30-minute changes, median curve fill) but the phrasing is domain jargon rather than a clear statement of what the tool returns. It does not distinguish itself from the sibling tool day_full_stats, leaving the agent to guess which one to call.

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?

There is no guidance on when to use this tool versus day_full_stats or wallet_day. The only routing instruction is 'Use days_available for the exported UTC day range,' which points to a helper tool rather than explaining selection criteria for this tool.

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