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

Annotations cover only readOnly/openWorld, so the description carries real weight and delivers it: 20% tapering to 0% over 366-730 days, a $20,000 deduction gated on 365+ days held. That is genuine model behavior beyond structured fields, though it doesn't note estimation limits or whether other exemptions (e.g. deaths, divorces) are handled.

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?

One dense sentence, rate schedule front-loaded followed by the deduction condition. No filler and no redundancy with the title or schema.

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 read-only calculator with a fully documented 3-parameter schema and no output schema, the description supplies the full rate model and deduction rule. It could still state whether the result is a plain tax amount or a breakdown, and confirm the estimate-only caveat.

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 already 100%, so the baseline is 3, but the description adds the interaction the schema does not spell out: the deduction applies only if held at least 365 days, which ties isPrimaryResidence to daysHeld and clarifies why taxableIncome can be negative.

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?

Specific verb ("Estimate") plus a precise resource ("British Columbia's home flipping tax") and scope ("sold within 730 days"). This clearly separates it from siblings like capital_gains_tax and house_flipping without needing to open the schema.

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 730-day window and residency condition imply the applicable scenario, but there is no explicit when-to-use instruction and no routing against the near-identical sibling "house_flipping". Usage is inferable rather than stated.

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