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

The annotations only provide readOnlyHint=false, idempotentHint=false, destructiveHint=false. The description goes far beyond this by disclosing exactly what changes and what does not: amount/currency/date are immutable, journal lines are rebuilt by relabelling the primary leg, balances are preserved, an audit_trail entry is written, and a ledger sync is re-queued. It also states the guards and side effects of create_rule, giving full behavioral transparency.

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?

The description is dense but every sentence earns its place. It is front-loaded with the core purpose, then flows logically through invariants, guards, the create_rule option, and actor_id defaults. The uppercase 'GUARDS' label structures the constraints clearly, and there is no filler or redundancy.

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?

Given the complexity (6 parameters, multiple guards, side effects), the description is complete: it explains preconditions, failure modes, side effects (audit, ledger sync, rule creation), parameter defaults, and validation. The presence of an output schema means return-value details are not needed, and the description covers everything an agent needs to invoke 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 description coverage is 100%, so the baseline is 3. The description does not add significant parameter-level meaning beyond the schema; it reinforces that there are no parameters for amount/currency/date and restates create_rule's forward-only behavior, but the schema already documents defaults, validation, and the chart-of-accounts values. No new parameter semantics are introduced.

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?

The description names a specific verb and resource: 'Changes the ACCOUNT on an already-posted entry (from the general ledger) and nothing else.' This clearly differentiates it from siblings like approve_classification (which handles unreviewed entries) and create_counterparty_rule (which creates forward rules without editing entries).

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?

Provides explicit when-to-use and when-not-to-use guidance: 'the entry must be posted (not awaiting review — use approve_classification for that); a manual or multi-leg entry cannot be reclassified (correct it by reversal); and an entry in a CLOSED period is refused (reopen or post a prior-period adjustment).' It also clarifies create_rule's relationship to counterparty rules, so an agent can route correctly.

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