Find eSIM plans for a country

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

Annotations already mark the tool as readOnly, openWorld, idempotent, and non-destructive. The description goes further by stating 'This needs no login,' warning that 'Prices are catalogue prices and may not include final tax,' and clarifying the result covers only the destination. These are meaningful behavioral disclosures beyond the annotations and do not contradict them.

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?

The description is structured with WHEN and AFTER SUCCESS sections, making it scannable. Every sentence provides actionable guidance: trigger condition, parameter handling, output formatting, scope limitation, and auth note. It is somewhat long but justified given the tool's complexity; no filler exists.

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?

Despite 9 parameters, the description covers the trigger, parameter discipline, result presentation (numbered list with bundle_code linkage), destination-only scope, pricing caveat, and no-login requirement. The presence of an output schema means return-value details are not needed in the description, and the post-success workflow is fully explained.

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 per-parameter explanations, so the baseline is 3. The description adds critical semantics for the country parameter ('Pass the country exactly as the user said it... Never invent a country identifier') and for filters ('Only pass a filter the user actually stated'), which meaningfully enriches parameter usage 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 opens with 'Find the eSIM plans available for one country,' a specific verb+resource+scope combination. It clearly distinguishes from the sibling tool find_bundles_by_region by emphasizing 'one country,' and the AFTER SUCCESS section reinforces this singular scope.

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 WHEN clause explicitly says to use this tool when 'the user names a destination country' and gives an example. It also instructs to only pass filters the user actually stated and mentions get_bundle_details as a follow-up tool. It does not explicitly name find_bundles_by_region as an alternative, though the distinction is implied.

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