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

Beyond the readOnly/non-destructive annotations, the description discloses a rich behavioral envelope: 366-day cap, default-to-today, exclusion of transfers and IOU anchors, separate listing of rows lacking an FX quote, a no-1:1-conversion rule, permission gating, and cost ($0.05; API key required). These are exactly the operational facts an agent needs and cannot get from structured fields.

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?

Effectively one dense paragraph, front-loaded with the core purpose and the aggregation detail. Every clause (date cap, FX caveat, permission, cost) carries information, though the heavy parentheticals make it slightly hard to scan.

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 an output schema present, return formatting need not be explained, and annotations cover the safety profile; the description adds the date-range, permission, and cost context on top. It is nearly complete, with the only soft spot being the absence of explicit guidance on choosing this over transaction-level siblings.

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 schema already documents all seven parameters, establishing the baseline of 3. The description reinforces the category parameter's matching semantics ('matches the expense category') and the single-display-currency model, but adds little that the schema descriptions do not already carry.

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 resource (money/finance totals for a civil date range) and precisely enumerates what is returned: total spent and income in one display currency, plus totals by category and by currency. It implicitly distinguishes itself from per-row tools by noting it is 'the same aggregation as Dayze chat' and that individual transactions require a separate permission, though it does not name a sibling directly.

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 tool is for aggregate finance totals, and the line about individual transactions needing the Financial details permission hints at the boundary with transaction-listing siblings. There is no explicit 'use X instead when Y' guidance, so the agent must infer when this beats get_transactions or get_expenses.

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