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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real behavioral context: a linked account is required (unlike streams_all and search) and it does not create a subscription or charge the user. It omits pagination/return behavior, but the schema and output schema cover that.

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?

Three sentences, zero waste: purpose and ordering first, then the account prerequisite, then sibling routing and side-effect clarification. Every clause earns its place and the key facts are front-loaded.

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 read-only browse tool with an output schema, the description supplies the remaining decision-relevant facts: auth prerequisite, sibling routing, and absence of side effects. Nothing needed to invoke it correctly 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 coverage is 100% with descriptive fields for limit, nextToken, queryType, and streamPackageCategory, so the schema carries parameter meaning. The description only implies default ordering ('most-subscribed first') and adds no format detail beyond it, making 3 the appropriate 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 (browse) and resource (stream packages), defines what a package is ('bundles of streams sold as one subscription'), and notes ordering ('most-subscribed first'). It explicitly distinguishes itself from streams_all, search, and list_my_stream_packages, so an agent can pick it without opening a 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 explicit routing: use this for the catalog, use streams_all/search when no linked account is needed, and use list_my_stream_packages for created or subscribed packages. Both when-to-use and when-not-to-use are covered with named alternatives.

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