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

Annotations already cover read-only, idempotent, non-destructive, and closed-world. The description adds valuable context: no sign-in required, billing granularity of 0.1 GiB, and that there is no fixed data package. This goes beyond what annotations provide, though it doesn't discuss rate limits or error behaviors.

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?

Three short sentences, front-loaded with the core purpose and pricing model, then optional parameter behavior and a key constraint (no sign-in). No wasted words.

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 annotations cover safety and idempotency, and no output schema exists, the description is largely complete: it explains the pricing model, optional estimation, billing granularity, and no sign-in requirement. Minor gaps remain around country parameter semantics and how the currency default is determined, but nothing critical for a read-only quote 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 description coverage is 67%. The description explains the gb value as optional for estimates and billed in 0.1 GiB steps, which adds meaning. However, it does not explain the country parameter or the currency options beyond what the schema already provides. The description partially compensates for the coverage gap but leaves country semantics unclear.

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 (quote) and resource (eSIM data), and clarifies the pricing model as pay-as-you-go per GB with no data package. Distinguishes from siblings like get_data_rate and get_esim_connection_check implicitly through the 'rate-checker' terminology, though it could be more explicit about the distinction.

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?

Provides clear context that this returns a per-GB price and that an optional gb value gives an estimate. Implies usage for pricing queries but does not explicitly state when to use this over get_data_rate or other quote tools. Explicit alternatives are missing but the context is clear enough.

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