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

The description explains return format (USD cents, cheapest first, pagination via next_offset). Annotations already indicate read-only and idempotent behavior. No contradictions; full transparency.

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, no wasted words, clearly communicates the tool's purpose and key features. Front-loaded with the main action.

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 complexity (7 params, no output schema), the description covers filter behavior, sorting, and pagination. Missing explicit mention of response fields, but sufficient for a search tool.

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% with each parameter described. The description adds minor context like 'prices in USD cents' and 'unlimited plans always match' but doesn't significantly enhance understanding beyond the 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 it searches the travel eSIM plan catalog with specific filters and sorting. It distinguishes from siblings like check_availability or get_plan by focusing on browsing/searching with multiple criteria.

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 implies this tool is for searching/exploring plans, but it doesn't explicitly state when to use it over siblings or when not to use it. However, the context from sibling names and the description's specificity provides adequate guidance.

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