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

The annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered elsewhere. The description adds useful behavioral context about the return payload (live lowest price, plan count) but says nothing about pagination, result ordering, or how 'live' pricing is refreshed.

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?

One sentence with the resource front-loaded, followed immediately by what distinguishes the results and the optional filter. No filler or redundant restatement of the title.

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 no output schema available, the description usefully enumerates what each entry contains (lowest live price and number of plans), which is exactly the gap it needs to fill. Coverage is close to complete for a simple one-parameter list tool, with only refresh/pagination behavior left unstated.

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% and the single 'search' parameter is already documented with examples in the schema. The description's 'filters by name' merely restates that, adding no new syntax or matching semantics, so the baseline of 3 applies.

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 names a specific resource (countries and regions Slashtel sells travel eSIMs for) and the exact payload it returns (lowest live price in USD plus plan count), which is far more concrete than the tool name alone. It does not, however, explicitly contrast itself with the sibling get_esim_plans, so the boundary between browsing destinations and browsing plans must be inferred.

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 mentions that an optional search filters by name, but never states when to reach for this tool versus get_esim_plans or the topup variants. An agent gets a sense of the tool's content but no routing guidance or prerequisites.

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