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

With no annotations, the description carries the full burden and does well: it discloses the computation model (cost method per country, ECB rate at trade date, year-of-sale rules, holding period, allowance, loss carry-forward) and a key caveat ('Not a tax return'). It omits auth/permission requirements and any rate-limit or performance notes.

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, front-loaded with the purpose and scope before the mechanics, and the caveat lands early enough to matter. The second sentence is a dense enumeration, but each clause carries distinct information rather than padding.

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 5-parameter, no-annotation, no-output-schema tool, the description covers the estimation model, the currency, the legal-scope caveat, and where to find country options. It leaves the return shape (fields, breakdown per trade/year) unspecified, which is a minor gap given no output schema exists.

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, but the description adds a genuinely useful pointer ('Each country's options are in list_tax_countries (options field)') that explains where the alternative/country option values come from. It does not add much beyond that for year or marginalRate, which the schema already documents.

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?

Opens with a specific verb+resource ('ESTIMATE of capital-gains tax in a country') and immediately scopes it ('in that country's currency', 'Not a tax return'), which cleanly separates it from siblings like get_realized_gains or get_pnl. An agent can identify the tool's job without opening 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?

It routes the agent to list_tax_countries for per-country options and states the estimate's scope, giving clear context for use. It stops short of explicitly naming when to prefer this over get_realized_gains or get_pnl, so no exclusions or alternatives are stated.

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