Download a sales or finance report

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

Annotations already declare readOnlyHint/openWorld/idempotent/non-destructive, so the safety profile is covered. The description adds real value beyond that: the payload is gzipped TSV, saving is optional, and the response includes row count, columns, totals and leading rows, plus the API key role requirement.

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, front-loaded with purpose and return behavior, followed by prerequisites. Dense but every clause carries information; only slight cost is the run-on packing of output fields.

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?

For a 10-parameter tool with no output schema, the description covers purpose, return shape, auth and the vendor-number sourcing fallback. Remaining gaps (report_type/frequency interplay, save path semantics) are largely handled by the schema's enums and field descriptions.

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 60%, and the description compensates by disclosing that vendor_number can alternatively come from the ASC_VENDOR_NUMBER environment variable – a fact absent from the schema – and by naming the required key role. It does not explain kind/frequency/report_sub_type semantics, but those carry enums and defaults.

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 (downloads) and resource (sales or finance report), plus the return format (Apple gzipped TSV) and what the tool yields. No sibling tool overlaps with report retrieval, so the agent can route to it unambiguously.

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?

Gives explicit prerequisites: the vendor number (with where to find it in App Store Connect) and a key carrying the Finance or Sales role. It does not spell out when-not-to-use or name alternatives, but no sibling tool competes for this task, so the guidance is effectively complete for context.

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