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

With no annotations, the description carries the full behavioral burden. It does disclose the return shape ('a single total number'), which is real value given there is no output schema, but it says nothing about whether transfers/refunds are included, permission requirements, or any rate limits. Adequate but thin for a zero-annotation tool.

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 tight sentences, zero filler, front-loaded with what it returns before the usage hint. 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 4-param read tool with no output schema and no annotations, the description covers purpose, return type, and use case, while the schema covers all parameter semantics. The remaining gap is edge-case behavior (what is included or excluded in the total), which an agent would plausibly want.

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 100% – defaults for startDate/endDate, the account filter, and the category-exclusion list are all documented in the schema. The description adds no syntax, format, or interpretation beyond that, so the baseline 3 applies.

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 total expense amount) plus the scope (a date range) and the return shape (a single total number). The 'single total number' framing cleanly separates it from the aggregate-breakdown siblings like get_spending_by_categories or get_cash_flow.

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?

Explicitly frames the use case ('quick how much did I spend queries instead of summing transactions manually'), which tells the agent when to reach for it over search_transactions. It does not name any sibling tool as an alternative or state when this tool is the wrong choice, so it stops short of a 5.

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