Merchant History

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, assuring safe read-only behavior. The description adds valuable behavioral details: substring matching on name/descriptor and the specific return fields (merchant, count, total_spent, etc.), which go beyond annotations without contradiction.

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 only two sentences, front-loaded with the main action and outcome. Every word is useful, with no repetition or fluff.

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 query tool with 3 params and known schema, the description covers input, output structure, and use cases. It could mention potential limitations (e.g., pagination or data range), but overall it provides sufficient context for effective use.

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 covers all 3 parameters with descriptions. The description adds that merchant is required and from/to are optional, and clarifies substring match for merchant. This adds some meaning beyond the schema but does not fully compensate for missing details (e.g., date format validation already in schema).

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 lists every charge from a given merchant with a spend summary, specifying substring matching on name/descriptor. It distinguishes from siblings like finance_search_transactions (broader search) or finance_spending_by_category (category-level) by focusing on a single merchant.

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 gives explicit use cases ('how much have I paid X' and 'spotting creep'), which helps the agent determine when to use this tool. However, it does not mention alternatives or when not to use it, leaving some ambiguity.

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