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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine behavioral context beyond them: the result is an estimate built on the receipt page's assumptions, not an authoritative assessment nor a record of the caller's actual payments — an important caveat for interpreting output.

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?

Two sentences, both front-loaded with the core capability first and the disclaimers second; nothing is redundant. 'Using the receipt page's assumptions' is slightly opaque but the phrasing is compact overall.

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 one-parameter, no-output-schema tool whose annotations cover safety, the description supplies the key missing pieces: what is computed (provincial tax estimate), what else is returned (spending shares), and what the result is not. Only the units/format of the numeric input remain unaddressed.

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?

The single parameter has 0% schema description coverage, so the description carries the burden. It clarifies that 'income' means annual employment income (rather than total or household income), but adds no currency, precision, or interpretation of the 0–10,000,000 bounds.

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 (Estimate) and resource (provincial income tax on annual employment income) and adds a second output (department spending shares). The negative clause ('Not a personal tax assessment or a trace of your tax payments') preempts the most likely misreading by an agent, so the tool is clearly separable from the generic get_*/search siblings.

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 establishes the operating context ('using the receipt page's assumptions') and an explicit exclusion ('not a personal tax assessment'). It does not name an alternative tool for when a real assessment is needed, but given no tax-related sibling exists, the routing guidance is adequate.

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