spending_summary_tool

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

The description indicates the tool is read-only ('reads the Plaid-shaped cache') and depends on prior syncing, but it does not disclose error behavior, data freshness, or whether it returns aggregated results directly or requires post-processing. This is partial transparency, not comprehensive.

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 concise, using two short sentences that quickly convey the core function and data source. The pipe-separated grouping options are a compact way to list alternatives, though slightly informal.

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?

Given the 3 parameters and an output schema, the description is incomplete: it does not explain parameter constraints, output structure, or how this tool relates to sibling tools like sync_transactions_tool. The mention of 'Plaid-only' and cache adds some context, but not enough for a new agent to use it effectively without additional investigation.

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 schema has zero description coverage for the three parameters (start_date, end_date, group_by). The description does not explain date formats, allowed group_by values, or how the default 'category' is applied, leaving critical usage details undefined.

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 the tool aggregates spending with flexible grouping ('by category | subcategory | merchant | account'), which is a specific and unambiguous purpose. The verb 'aggregate' and the listed dimensions precisely convey what the tool does.

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 description provides no explicit guidance on when to use this tool versus alternatives like search_transactions_tool or get_transactions_tool. It only mentions that it reads a cache populated by sync_transactions, which hints at a prerequisite but does not clarify selection criteria.

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