summarize

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

With no annotations provided, the description carries the burden of behavioral disclosure. It adds a non-obvious guarantee: 'Summing happens in Postgres over NUMERIC values, so the total is exact.' This is genuinely useful context about precision. It does not explicitly say the operation is read-only, but the aggregation wording and lack of mutation signals make that reasonably clear.

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?

The description is three short sentences, each earning its place: purpose, correctness guarantee, and usage preference. It is front-loaded with the primary function and contains no redundant filler or repeated schema content.

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 read-only aggregate tool with three optional parameters and a present output schema, the description covers purpose, usage guidance, and an important behavioral guarantee. Any remaining edge cases (e.g., empty results, invalid date ranges) are not essential for an agent to invoke the tool correctly, especially since the output schema and parameter descriptions provide the rest.

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%, so the schema already fully documents all three parameters. The description only restates the date-range and category-breakdown concepts, adding no new meaning about date formats, inclusive bounds, or the categorical behavior beyond what the schema provides. Baseline 3 is appropriate.

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: 'Total spending over a date range, broken down by category.' This clearly conveys the aggregation behavior and differentiates it from sibling tools like list_expenses. The phrase 'Prefer this over listing every row' reinforces that it summarizes rather than enumerates.

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 instruction 'Prefer this over listing every row and adding them up' explicitly tells the agent to use this tool for totals rather than manually aggregating list results. It does not name the sibling tool list_expenses directly, nor does it state exclusions (e.g., 'use list_expenses when line items are needed'), so it falls just short of fully explicit alternative routing.

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