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

Annotations already carry readOnlyHint/destructiveHint, so the bar is lower, yet the description still adds real value: it discloses data provenance ('the vendor's own records, not our observation'), the exact shape of what is returned (counts, monthly frequency, durations, weekday/hour patterns in JST, source URLs), and the empty-state sentinel found:false. It does not mention pagination or how the 1-30 limit interacts with the aggregates.

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?

A dense but front-loaded single sentence that leads with what the tool returns, followed by two short high-value fragments (Read-only; found:false meaning). Every clause carries information, though the parenthetical asides make it slightly heavy to parse in one pass.

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 carries the burden of describing returns and does so thoroughly — aggregate counts and frequencies, durations, weekday/hour patterns, recent records, and source URLs — plus provenance and the not-collected signal. An agent has everything needed to call and interpret this tool 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 coverage is 100%, so both slug and limit are already documented in the schema. The description only reinforces 'one system' (slug) and 'recent records' (limit) without adding format, constraints, or default behavior beyond the schema; baseline 3 is appropriate.

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 and scope: 'vendor-published incident history and announced maintenance for one system'. The word 'history' implicitly separates it from the sibling renkeimap_status, but the description never names that sibling or explicitly contrasts past-vs-current, so differentiation is left to the reader.

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 caller must infer this is the tool for retrospective incident/maintenance data rather than current state. There is no explicit 'use this when...' or 'for live status use renkeimap_status' routing, though 'found:false = not collected yet' does hint at an empty-state condition worth knowing before calling.

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