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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuine behavior beyond that: the data is scoped to the signed-in person only, values are 'counted by the filing rule' (a computation caveat), and it discloses that undecided transactions are surfaced as a count. It does not mention caching, latency, or cost.

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 but well-structured sentence, front-loaded with the identity of the result ('the signed-in person's tax year so far') before the itemised contents. Every clause maps to a distinct returned field with no filler, though the comma-list is long enough that it reads as a run-on.

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?

There is no output schema, so the description must define the return payload itself, and it does so exhaustively: income, expenses, profit, estimated income tax, Class 4 NI, undecided-transaction count, filed quarterly updates, and next deadline, plus the signing-rule caveat. Nothing material is missing for a single-parameter read tool.

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?

With schema description coverage at 100% and an enumerated taxYear parameter whose default is documented ('Defaults to the current tax year'), the schema fully carries parameter meaning. The description only implies a year scope via 'tax year so far' and adds no enum values, format, or behavior for out-of-range years, so baseline 3 is correct.

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+resource (the signed-in person's tax position for the year) and enumerates the exact scope of that position: income, expenses, profit, tax and Class 4 NI, undecided transactions, filed quarterly updates, next deadline. It is highly concrete, but it never names or contrasts with the overlapping siblings estimate_self_employed_tax, check_mtd_status, or get_mtd_deadlines, so an agent must infer the boundary.

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?

Usage is implied rather than stated: the description frames the tool as 'the TapTax dashboard view', which signals it is the aggregate overview rather than a point calculation. There is no explicit when-to-use, when-not-to-use, or alternative ('use X for a single estimate'), and the overlap with estimate_self_employed_tax and get_mtd_deadlines is left unresolved.

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