expense_summary

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

Annotations already indicate read-only, idempotent behavior. The description adds that it returns a summary with totals, balance, and category breakdown, which is useful. However, it does not disclose any edge cases, data recency, or limitations beyond the basic output shape.

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 extremely concise: two sentences plus a brief Args/Returns section. The purpose is front-loaded, and every word adds value. No unnecessary text.

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 tool with one parameter and an output schema, the description covers the essential: what it does, the parameter options, and the return structure. The missing default and lack of usage guidance are minor gaps given the tool's simplicity and the presence of annotations and output 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?

The description explicitly lists the allowed values for the period parameter ('today', 'week', 'month', 'year'), which is not described in the input schema (coverage 0%). This adds meaning beyond the enum definition. However, it does not mention the default value 'month', which is present in the schema, missing an opportunity to fully inform the agent.

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 clearly states 'Get spending summary for a time period', identifying the action and resource. It mentions the return includes totals, balance, and category breakdown. However, it does not differentiate from sibling tool 'expense_insights', which might also provide summary data, slightly reducing clarity.

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?

No guidance is provided on when to use this tool versus alternatives like expense_insights or expense_search. No context on when not to use it or prerequisites is given, leaving the agent to infer usage from the name alone.

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