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

Annotations already carry readOnly/idempotent/non-destructive, and the description adds genuinely new behavior: the source systems covered, that per-account sync errors are surfaced, and the precise staleness rule (stale=true when older than stale_hours or never synced). It doesn't mention cost, sorting, or ordering of the returned accounts, which keeps it from a 5.

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?

Two sentences, front-loaded with the read tag and the subject (data freshness), then the usage rule. The parenthetical list of sources is long but is load-bearing for deciding coverage; slightly tighter phrasing would earn a 5.

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 no-output-schema status tool with one optional parameter, the description explains the returned fields and staleness logic well enough to call and interpret it. It omits nothing critical, though a note on whether all accounts are always returned (including never-synced ones) would fully close the loop.

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 0%, so the description must carry the single parameter — and it does, defining stale_hours as the staleness threshold with a stated default of 26 and tying it to the stale flag. Only the unit semantics (hours, confirmed by the name) are left implicit.

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 ([read] Data freshness) and enumerates exactly what the response contains: per-account last sync times, hours since the main sync, sync errors, and a stale flag. An agent can distinguish this from the sibling sync_* tools (which mutate) without opening the schema.

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?

'Use it before a report to say which numbers may be out of date' gives a concrete trigger condition. No explicit when-not-to-use or named alternative, so it stops short of the top score, but the intended call point is unambiguous.

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