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 accounting method (FIFO), currency, that fees and gas are deducted, and the return shape (total/per asset/per year). It omits any statement about permissions, data freshness, or whether the result is read-only/cached, which keeps it short of a 5.

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 plus a three-word caveat, front-loaded with the resource and method. Every clause (FIFO, euros, fees/gas, aggregation levels) earns its place and nothing is padded.

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?

With no output schema, the description compensates by describing the return structure, and it covers method and deductions. For a single-optional-parameter read tool this is nearly complete; only the absence of any read-only/safety statement and empty-result behavior keeps it from a 5.

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 description coverage is 100% and the single 'year' parameter is fully documented in the schema, including the optional/return-everything behavior. The description's 'per year' phrasing reinforces the grouping dimension but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 the exact resource (realised capital gains), the calculation method (FIFO), currency (euros), and deductions (fees and gas), plus the aggregation levels (total, per asset, per year). This is specific enough to separate it from get_pnl and get_tax_estimate, though it never names a sibling 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?

The closing caveat 'Not a tax return' implicitly steers the agent toward get_tax_estimate for filing purposes, which is a useful negative signal. However, there is no positive statement of when to prefer this tool, no prerequisite or scope guidance beyond that one caveat.

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