get_balance_history

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

readOnlyHint=true is already covered by annotations, so the description is free to add real value: it discloses downsampling behavior (keeping the last data point per period) and that the accounts array reflects the paginated page. These are non-obvious behavioral traits beyond the annotations, though pagination/limit interaction and freshness are not spelled out.

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?

Front-loaded with the core purpose, then return shape, then the granularity/downsampling caveat. Every sentence carries information; only the restatement of the required granularity slightly overlaps with the 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?

With no output schema, the description compensates by enumerating the returned fields (current_balance, available_balance, limit, account_id, account_name) and the accounts array. It covers the key non-obvious behavior (downsampling), leaving only secondary details like cache vs live data and error/empty behavior unaddressed.

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; the description earns above that by explaining the semantic effect of granularity (downsampling via last data point per period) beyond the enum values, and noting account_id/date-range filtering. This adds meaning the schema alone does not convey.

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 and resource: 'Get daily balance snapshots for accounts over time,' which distinguishes it from siblings like get_transactions, get_goal_history, and get_investment_prices that return different resource types. It doesn't name siblings explicitly, but the resource is unambiguous.

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?

Gives useful intra-tool guidance ('use weekly or monthly for longer time ranges'), but offers no explicit when-to-use-this-vs-alternatives guidance relative to the many sibling read tools, nor any prerequisites/exclusions. Usage is implied rather than stated.

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