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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds nothing beyond that: it doesn't say whether uncategorized transactions appear as a bucket, how categories are keyed, or how totals are shaped, which for an aggregation tool is where the real ambiguity lives.

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 or repetition. It is efficient, though its brevity is partly the source of the gaps in the other dimensions.

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 simple two-param read tool with full schema coverage and complete annotations, the essentials are present. But with no output schema, the description should say roughly what an aggregated-by-category response looks like, and it doesn't.

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%, with both start and end documented as ISO YYYY-MM-DD, so the schema carries the load. 'For a date range' adds nothing the schema doesn't already provide, making the baseline 3 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?

The description states a specific verb and resource ('Get spending aggregated by category'), so an agent knows exactly what it returns. It does not, however, distinguish itself from the near-identical sibling spending_by_merchant, which a one-clause contrast would have settled.

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 only usage signal is the phrase 'for a date range', which restates the required params. There is no statement of when to prefer this over spending_by_merchant, list_transactions, or search_transactions, all of which could surface overlapping data.

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