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

Annotations already declare readOnlyHint=true, so read-only safety is clear. The description adds that results include actual purchased item names for matching expenses, which is useful return-content context, but doesn't mention pagination, default limit behavior, or sort order beyond the schema hints.

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 sentences, front-loaded with the core action and keyword scope, followed by return-value guidance. Minor wordiness but no filler.

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 read-only search with a fully documented schema, the description covers purpose and the key output characteristic (item names). It omits sibling differentiation and result-ordering/pagination context, which leaves a small gap.

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%, so all four parameters (query, limit, startDate, endDate) are documented in the schema. The description clarifies query matches merchant or item name but adds no meaning about limit, dates, or keyword behavior beyond that.

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 (search) and resource (expenses) and clarifies the keyword matches merchant or item name. It distinguishes itself somewhat by emphasizing 'what products/groceries' via returned item names, but does not explicitly contrast with siblings like get_top_products or get_expenses.

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?

Implies usage for finding purchased item names by keyword, but offers no explicit when-to-use vs alternatives (e.g., get_top_products, get_top_merchants, get_expenses). The agent must infer selection from the brief context.

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