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

readOnlyHint=true already covers the safety profile, so the bar is lower. The description adds the useful default ('today') and the underlying endpoint (GET /v2/accounting/balance_sheet), but says nothing about auth requirements, response shape, or whether comparative periods are returned.

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?

A single front-loaded sentence with no filler; the resource and its contents come first, the scoping clause and endpoint reference follow. Every clause earns its place.

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-optional-parameter, read-only reporting tool with no output schema, the description covers purpose, contents, default date, and the endpoint. Return structure is only hinted at via the line-item enumeration, which is acceptable but slightly thin.

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 default value ('default today') that the schema itself does not encode as a default. That is a genuine increment over the structured field for this single optional parameter.

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 ('Balance sheet') and enumerates its contents ('capital and current assets, liabilities and owners' equity') plus the temporal scope. This effectively separates it from the sibling freeagent_get_profit_and_loss without naming it, though no explicit sibling differentiation is stated.

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 implies usage through the 'as at a date (default today)' scoping and the accounting context, but never says when to prefer it over freeagent_get_profit_and_loss or the other financial reporting siblings. 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.