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

Beyond the annotations' destructiveHint/idempotentHint, the description discloses the quota consequence (free-tier slot released), the guard condition that blocks deletion, and that the blocking month is named in the refusal. That is exactly the extra context an agent needs before firing a destructive call, and it also scopes the blast radius.

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 destructive action and its payoff, followed by the refusal rule and scope note. No sentence is redundant.

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 three-parameter destructive toggle with a fully documented schema and no output schema, the description covers purpose, guard condition, and side effects. The only minor gap is what a successful call returns, which the absence of an output schema makes low stakes.

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%: the from/to date formats and the conditional currency requirement are already fully documented in the schema. The description refers only to "the period" without adding format or disambiguation detail, so it meets but does not exceed the 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?

"Delete one built period from the register" gives a specific verb plus resource and narrows scope to a single period, so it cannot be confused with ledger_build or month_close. The quota side effect ("give its free-tier slot back") further fixes what kind of delete this is.

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?

The description states a concrete when-not condition (refused when a closed month's snapshot covers the period) and clarifies blast radius with "No sibling book is touched." It does not name a sibling alternative to use instead, but with no competing delete tool in the set there is little to route between.

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