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

With no annotations, the description carries the burden and does well: it discloses that rates are not auto-resolved, that changes are non-retroactive (new quotes and invoices only), and what is_default controls. It omits permission requirements and what happens to existing records on update.

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?

Four tight sentences, front-loaded with the action and immediately followed by the highest-risk unit detail. The parenthetical '(owner or office)' is slightly ambiguous but costs little.

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 6-parameter mutation tool with no annotations and no output schema, the description covers the semantics that matter most (unit, default flag, retroactivity). The gap is the update path: it never states that tax_rate_id must be supplied to change an existing rate rather than create one.

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 only 17%, so the description must compensate, and it does for the two most error-prone fields: rate_bps is defined as hundredths of a percent with a worked example (600 = 6%), and is_default's resolution behavior is explained. name and tax_rate_id remain unexplained, though 'add or change' hints at the latter.

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 pair and resource: 'Add or change a sales tax rate the shop charges in one jurisdiction.' This clearly separates it from taxes_listRates, taxes_archiveRate and taxes_salesReport by implication, though no sibling is named explicitly.

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?

'You enter the rate; Doing Work never looks it up' gives a useful precondition, and the new-quotes-only note scopes the effect. But it never says when to use this versus taxes_listRates (to find a tax_rate_id) or taxes_archiveRate, so the agent must infer the workflow.

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