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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds real value beyond that: it discloses that values are never estimated, that they match the in-app view, and that results may include stale sources, pending-review items and AI-added entries — data-quality traits an agent could not infer from annotations.

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?

Two sentences, front-loaded with the core definition and then the caveat about row sums. Dense but every clause carries substance; the enumerated result fields are somewhat list-like but not redundant.

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 correctly enumerates the returned fields an agent needs to know about. It is close to complete for a single read-only retrieval tool; the main omission is the default time window when from/to are omitted, which the description leaves to the schema.

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 80%, and the schema itself carries very rich per-enum documentation for metric and basis, so the schema does the heavy lifting. The description adds no parameter-specific syntax or default behavior (e.g. what omitting from/to means), so the baseline 3 holds.

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?

The description defines the resource precisely — a fixed-definition Aggregate-computed metric returned with value, basis, as-of time, formula, included/excluded accounts, stale sources and review counts. It distinguishes the result from a naive sum of transaction rows. It does not, however, name which sibling to use instead (e.g. query_transactions) for the underlying rows.

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?

There is no explicit when-to-use or when-not-to-use guidance, and no alternative tool is named. The only usage-adjacent statement is the warning that a sum of listed rows may not match, which is a caveat rather than routing guidance.

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