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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), but the description adds genuinely useful behavior the annotations cannot: the overview can be null because it is written only after the day ends, and days expire after 30 days. It does not cover pagination or failure modes, which is a minor gap.

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-loads the core purpose, then usage examples, then defaults and return shape — a logical progression with little filler. Slightly dense in the middle sentence, where three separate facts are packed together.

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?

An output schema exists, so return values need not be spelled out, yet the description helpfully flags the null-overview caveat and the ranking (score and heat) plus asOf. Combined with full schema coverage and a closed-world annotation, an agent has what it needs to call this correctly.

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%, so date, limit and niche are already documented in the schema, including the same defaults (last finished day, default 10 / max 25) that the description restates. The description adds no format or edge-case detail beyond the schema, so the 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?

States a specific verb and resource — retrieve one UTC day's events plus an overview paragraph — and the day-scoping plus 'digest' framing implicitly separates it from siblings like latest_events and search_events. It never names a sibling explicitly, so the differentiation is inferred rather than stated.

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?

Gives concrete trigger phrasing ('give me yesterday's digest', 'what happened on 2026-10-20?') and clarifies the default date behavior and 30-day retention window. It does not state when to prefer latest_events or search_events instead, so the alternative-selection rule is left implicit.

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