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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the bar is lower. The description does add two useful behaviors beyond structured data: US-only scope and the fact that results arrive sorted by bonus value descending. It says nothing about pagination behavior or how the limit interacts with total matches.

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: the trigger condition is front-loaded and the return behavior follows. Every clause earns its place with no restatement of the name or schema.

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?

With full schema coverage, an output schema, and annotations present, the description need not explain parameters or return fields. What it covers is sufficient to invoke the tool, though it omits any routing hint among the four sibling bonus tools.

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%, with every parameter documented including enum values and the state-matching rule, so the schema carries the parameter burden. The description adds no filtering syntax or format detail beyond it, making the baseline 3 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?

Names a specific verb and resource ('find a US bank account, savings, or credit card signup bonus'), and adds a second intent ('asks which offers are worth opening'). It also states the return ordering. It stops short of naming or contrasting the siblings (get_bonus, compare_bonuses, expiring_soon), so an agent must infer which search-style tool applies.

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?

'Use when a user wants to find...' gives a clear triggering context, and the mention of 'which offers are worth opening' broadens the recognized intent. However, no exclusions or alternatives are stated, so it never says when to prefer compare_bonuses or expiring_soon over this tool.

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