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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds real value beyond that: credential-free public data, direct reads from the store's promotion-products API, and the rejection behavior for invalid media_type. Return shape is left to the output schema, which exists.

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?

Front-loaded with the core definition and the exclusion of neighboring shelves before peripheral detail. The inline Country and Locale lines duplicate the schema, which is mild redundancy, but every other sentence earns its place.

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 annotations covering safety and an output schema covering the return payload, the description supplies the remaining context an agent needs: scope of the shelf, valid media types, data source, and the sibling alternative. Nothing material is missing.

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 schema already documents MediaType, Country (ISO-2, default US), and Locale (BCP-47, default en-US). The description largely repeats these defaults and the allowed media_type values rather than adding syntax or format meaning, so it sits at the baseline.

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 and resource ('Returns the curated hero/spotlight shelf'), and explicitly distinguishes it from sibling surfaces: the ranked charts (microsoftstore_charts) and the smaller 'Special events' shelf (microsoftstore_events). An agent can tell it apart from other microsoftstore tools without opening any schema.

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 clear applicability boundaries: only home, apps, and games have a spotlight, any other media_type is rejected, and it routes the agent to microsoftstore_editorial for editorial articles by id. It stops short of a fully explicit 'use this when X, otherwise Y' directive, but the disqualifying context is strong.

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