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

Annotations already indicate a non-read-only, non-destructive, idempotent operation, and the description adds substantial behavioral detail beyond that: deactivation never deletes, existing transactions remain visible in the P&L, refusal conditions, audit-trailing, and actor_id attribution constraints. No contradiction with annotations.

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 dense sentences carry all the essential information with no filler. The description is front-loaded with the primary action and effect, then covers constraints and parameter edge cases. Every clause earns its place.

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 output schema exists, the description does not need to explain return values. It covers the tool's core behavior, non-destructive nature, refusal cases, audit trail, and the actor_id safeguard. Together with the schema and annotations, an agent has everything needed to decide when and how to invoke it.

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 the baseline is 3. The description adds meaning beyond the schema by explaining the real-world effect of active=false, the refusal conditions tied to account_id, and the audit-trail implication of the reason parameter. This extra context pushes it above 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?

The description states a specific verb ('deactivates'/'reactivates') applied to a specific resource ('a chart account'), and immediately clarifies the operational meaning of deactivation. This distinguishes it clearly from sibling tools like rename_chart_account or add_chart_account.

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?

It gives clear context on when this tool applies: to hide or unhide a chart account from new categorisation. It also states explicit refusal conditions for system accounts and accounts referenced by counterparty rules. However, it does not explicitly name alternative siblings or say 'use X instead when...', so it falls just short of a 5.

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