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

Annotations already declare readOnlyHint=true, so the trailing 'Read-only' is redundant, but the description adds substantive behavioral context the annotations cannot: the exact precedence rules that determine which window is returned. It remains silent on edge cases (e.g. what happens with no entries at all), keeping it below 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?

Three short sentences, front-loaded with the core purpose, then the resolution rules, then the read-only note. No filler and no repetition of schema or annotation content beyond a one-word safety restatement.

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-format detail is unnecessary, and the description still explains the logic behind the returned window. For a single-parameter read tool this covers what an agent needs, though it could note failure behavior when no close target is derivable.

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?

Only one parameter, and the schema documents it at 100% coverage, so the schema carries the load. The description adds nothing about the companyId semantics or the UUID wrapper, making 3 the correct baseline.

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+resource: it returns the accounting window the next close must cover, and it spells out the resolution precedence (reopened period > month after closed-through > month of first entry). An agent can distinguish this from generic period getters. It does not name the nearest sibling (e.g. accounting_preview_close) to contrast against, so it stops short of 5.

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 implied by the mention that these are 'the same rules ClosePeriod enforces', which situates it before a close workflow, but there is no explicit when-to-use or when-not-to-use statement and no named alternative such as accounting_preview_close or accounting_get_list_periods.

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