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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety and idempotency profile is fully covered structurally. The description adds only two behavioral facts beyond that: results are limited to 'public sellable' plans, and purchasing is out of scope. It says nothing about result ordering, pagination, or what is returned when no plans match.

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 short, front-loaded sentences with no filler or redundancy. The brevity comes at some cost to completeness, but nothing unnecessary is present.

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?

There is no output schema, so the description carries the burden of indicating what comes back, yet it never says the response is a list of plans with prices. Combined with the undocumented filter parameters and the unstated destination format, an agent cannot confidently construct a call beyond the required destination string.

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 0% and the description only clarifies that filtering is 'by destination'. It does not explain the destination slug format (enforced by a regex pattern), nor does it mention the three optional filter parameters limit, min_data_gb and min_validity_days, which are entirely undocumented in both schema and description.

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 clear verb and resource ('Search public sellable eSIM plans and prices') scoped by destination, which is more specific than the title. It does not explicitly distinguish itself from the sibling list_travel_esim_destinations, so an agent must infer that this one returns plans/prices while the sibling returns destinations.

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 sentence 'Purchase happens on the SimVoro website' implies this tool is browse-only and that no transaction can be completed here, which is useful implied usage. However, there is no explicit statement of when to use this versus list_travel_esim_destinations or check_esim_device_compatibility, and no prerequisites or exclusions are given.

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